<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with WebFilings-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://mcry.com/role/AcquiredIntangibleAssets" xlink:href="mrcy-20130630.xsd#AcquiredIntangibleAssets" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/AcquiredIntangibleAssetsDetail" xlink:href="mrcy-20130630.xsd#AcquiredIntangibleAssetsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/AcquiredIntangibleAssetsTables" xlink:href="mrcy-20130630.xsd#AcquiredIntangibleAssetsTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/Acquisitions" xlink:href="mrcy-20130630.xsd#Acquisitions" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/AcquisitionsAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#AcquisitionsAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/AcquisitionsNetPurchasePriceAndPreliminaryAllocationForAcquisitionDetail" xlink:href="mrcy-20130630.xsd#AcquisitionsNetPurchasePriceAndPreliminaryAllocationForAcquisitionDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/AcquisitionsSupplementalStatementsOfOperationsInformationDetail" xlink:href="mrcy-20130630.xsd#AcquisitionsSupplementalStatementsOfOperationsInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/AcquisitionsTables" xlink:href="mrcy-20130630.xsd#AcquisitionsTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/CommitmentsAndContingencies" xlink:href="mrcy-20130630.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/CommitmentsAndContingenciesAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#CommitmentsAndContingenciesAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/CommitmentsAndContingenciesTables" xlink:href="mrcy-20130630.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ComponentsOfIncomeBeforeIncomeTaxesAndIncomeTaxExpenseBenefitDetail" xlink:href="mrcy-20130630.xsd#ComponentsOfIncomeBeforeIncomeTaxesAndIncomeTaxExpenseBenefitDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ComponentsOfNetDeferredTaxAssetsLiabilitiesDetail" xlink:href="mrcy-20130630.xsd#ComponentsOfNetDeferredTaxAssetsLiabilitiesDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ConsolidatedBalanceSheets" xlink:href="mrcy-20130630.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="mrcy-20130630.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="mrcy-20130630.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveIncomeLoss" xlink:href="mrcy-20130630.xsd#ConsolidatedStatementsOfOperationsAndComprehensiveIncomeLoss" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ConsolidatedStatementsOfShareholdersEquity" xlink:href="mrcy-20130630.xsd#ConsolidatedStatementsOfShareholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/Debt" xlink:href="mrcy-20130630.xsd#Debt" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/DebtAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#DebtAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/DescriptionOfBusiness" xlink:href="mrcy-20130630.xsd#DescriptionOfBusiness" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/DescriptionOfBusinessDetails" xlink:href="mrcy-20130630.xsd#DescriptionOfBusinessDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/DocumentAndEntityInformation" xlink:href="mrcy-20130630.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/EmployeeBenefitPlans" xlink:href="mrcy-20130630.xsd#EmployeeBenefitPlans" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/EmployeeBenefitPlansAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#EmployeeBenefitPlansAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/EstimatedFutureAmortizationExpenseForAcquiredIntangibleAssetsDetail" xlink:href="mrcy-20130630.xsd#EstimatedFutureAmortizationExpenseForAcquiredIntangibleAssetsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ExpensesByBusinessSegmentForRestructuringPlansDetail" xlink:href="mrcy-20130630.xsd#ExpensesByBusinessSegmentForRestructuringPlansDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/FairValueOfAcquiredAssetsDetail" xlink:href="mrcy-20130630.xsd#FairValueOfAcquiredAssetsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/FairValueOfFinancialInstruments" xlink:href="mrcy-20130630.xsd#FairValueOfFinancialInstruments" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/FairValueOfFinancialInstrumentsAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#FairValueOfFinancialInstrumentsAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/FairValueOfFinancialInstrumentsTables" xlink:href="mrcy-20130630.xsd#FairValueOfFinancialInstrumentsTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/Goodwill" xlink:href="mrcy-20130630.xsd#Goodwill" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/GoodwillAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#GoodwillAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/GoodwillChangesInCarryingAmountOfGoodwillDetail" xlink:href="mrcy-20130630.xsd#GoodwillChangesInCarryingAmountOfGoodwillDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/GoodwillTables" xlink:href="mrcy-20130630.xsd#GoodwillTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/IncomeTaxes" xlink:href="mrcy-20130630.xsd#IncomeTaxes" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/IncomeTaxesAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#IncomeTaxesAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/IncomeTaxesTables" xlink:href="mrcy-20130630.xsd#IncomeTaxesTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/Inventory" xlink:href="mrcy-20130630.xsd#Inventory" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/InventoryAdditionalInformationDetails" xlink:href="mrcy-20130630.xsd#InventoryAdditionalInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/InventoryDetail" xlink:href="mrcy-20130630.xsd#InventoryDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/InventoryTables" xlink:href="mrcy-20130630.xsd#InventoryTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/MinimumLeasePaymentsUnderNonCancelableOperatingLeasesDetail" xlink:href="mrcy-20130630.xsd#MinimumLeasePaymentsUnderNonCancelableOperatingLeasesDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomers" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomers" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomersAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersCustomersComprisingTenPercentOrMoreRevenuesDetail" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomersCustomersComprisingTenPercentOrMoreRevenuesDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersGeographicDistributionOfRevenuesAndLongLivedAssetsFromContinuingOperationsDetail" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomersGeographicDistributionOfRevenuesAndLongLivedAssetsFromContinuingOperationsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersReconcilesNetIncomeMostDirectlyComparableGaapFinancialMeasureToAdjustedEbitdaDetail" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomersReconcilesNetIncomeMostDirectlyComparableGaapFinancialMeasureToAdjustedEbitdaDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersSummaryOfPerformanceOfOperationsByReportableSegmentDetail" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomersSummaryOfPerformanceOfOperationsByReportableSegmentDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersTables" xlink:href="mrcy-20130630.xsd#OperatingSegmentGeographicInformationAndSignificantCustomersTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/PropertyAndEquipment" xlink:href="mrcy-20130630.xsd#PropertyAndEquipment" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/PropertyAndEquipmentAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#PropertyAndEquipmentAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/PropertyAndEquipmentDetail" xlink:href="mrcy-20130630.xsd#PropertyAndEquipmentDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/PropertyAndEquipmentTables" xlink:href="mrcy-20130630.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ReconciliationBetweenStatutoryFederalIncomeTaxRateAndEffectiveIncomeTaxRateFromContinuingOperationsDetail" xlink:href="mrcy-20130630.xsd#ReconciliationBetweenStatutoryFederalIncomeTaxRateAndEffectiveIncomeTaxRateFromContinuingOperationsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/RestructuringPlan" xlink:href="mrcy-20130630.xsd#RestructuringPlan" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/RestructuringPlanAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#RestructuringPlanAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/RestructuringPlanTables" xlink:href="mrcy-20130630.xsd#RestructuringPlanTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/RollForwardOfFairValueOfContingentConsiderationDetail" xlink:href="mrcy-20130630.xsd#RollForwardOfFairValueOfContingentConsiderationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ShareholdersEquity" xlink:href="mrcy-20130630.xsd#ShareholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/ShareholdersEquityAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#ShareholdersEquityAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensation" xlink:href="mrcy-20130630.xsd#StockBasedCompensation" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensationAdditionalInformationDetail" xlink:href="mrcy-20130630.xsd#StockBasedCompensationAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensationStockBasedCompensationExpensesDetail" xlink:href="mrcy-20130630.xsd#StockBasedCompensationStockBasedCompensationExpensesDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensationSummaryOfNonvestedRestrictedStockDetail" xlink:href="mrcy-20130630.xsd#StockBasedCompensationSummaryOfNonvestedRestrictedStockDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensationSummaryOfStockOptionPlansDetail" xlink:href="mrcy-20130630.xsd#StockBasedCompensationSummaryOfStockOptionPlansDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensationTables" xlink:href="mrcy-20130630.xsd#StockBasedCompensationTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/StockBasedCompensationWeighedAverageKeyAssumptionsAndFairValueResultsForStockOptionsGrantedDetail" xlink:href="mrcy-20130630.xsd#StockBasedCompensationWeighedAverageKeyAssumptionsAndFairValueResultsForStockOptionsGrantedDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SubsequentEvents" xlink:href="mrcy-20130630.xsd#SubsequentEvents" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfFinancialAssetsMeasuredAtFairValueOnRecurringBasisDetail" xlink:href="mrcy-20130630.xsd#SummaryOfFinancialAssetsMeasuredAtFairValueOnRecurringBasisDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfReservesForUnrecognizedIncomeTaxBenefitsDetail" xlink:href="mrcy-20130630.xsd#SummaryOfReservesForUnrecognizedIncomeTaxBenefitsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesAccumulatedOtherComprehensiveIncomeDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesBasicAndDilutedWeightedAverageSharesOutstandingDetail" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesBasicAndDilutedWeightedAverageSharesOutstandingDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesChangesInProductWarrantyAccrualDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesChangesInProductWarrantyAccrualDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesConcentrationOfRiskDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesConcentrationOfRiskDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesIncomeTaxesDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesIncomeTaxesDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesIntangibleAssetsDetail" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesIntangibleAssetsDetail" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesNetEarningsPerShareAdditionalInformationDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesNetEarningsPerShareAdditionalInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesPrinciplesOfConsolidationDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesPrinciplesOfConsolidationDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesReclassificationDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesReclassificationDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesRestrictedCashDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesRestrictedCashDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesRevenueRecognitionDetails" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesRevenueRecognitionDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="mrcy-20130630.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SupplementaryInformationUnaudited" xlink:href="mrcy-20130630.xsd#SupplementaryInformationUnaudited" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SupplementaryInformationUnauditedDetails" xlink:href="mrcy-20130630.xsd#SupplementaryInformationUnauditedDetails" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/SupplementaryInformationUnauditedTables" xlink:href="mrcy-20130630.xsd#SupplementaryInformationUnauditedTables" xlink:type="simple" />
  <roleRef roleURI="http://mcry.com/role/UnamortizedDeferredGainDetail" xlink:href="mrcy-20130630.xsd#UnamortizedDeferredGainDetail" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <definitionLink xlink:role="http://mcry.com/role/AcquiredIntangibleAssets" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/AcquiredIntangibleAssetsDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7E6E1BF6CB9DBD85BEEC747DD967AB25" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_8C94AE6B411F49B20C28747DD9660D6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7E6E1BF6CB9DBD85BEEC747DD967AB25" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_8C94AE6B411F49B20C28747DD9660D6B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_F3BF947A20612DF8D267747DD96716E7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_8C94AE6B411F49B20C28747DD9660D6B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_F3BF947A20612DF8D267747DD96716E7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_F3BF947A20612DF8D267747DD96716E7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_F3BF947A20612DF8D267747DD96716E7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_45C437CF852C3EC23577747DD967EB80" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:to="loc_us-gaap_CustomerRelationshipsMember_45C437CF852C3EC23577747DD967EB80" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PatentsAndLicensingRightsMember" xlink:label="loc_mrcy_PatentsAndLicensingRightsMember_FC98024D75E5DA947BAE747DD96711DD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:to="loc_mrcy_PatentsAndLicensingRightsMember_FC98024D75E5DA947BAE747DD96711DD" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CompletedTechnologyMember" xlink:label="loc_mrcy_CompletedTechnologyMember_B20A1578143C90505B07747DD967B510" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:to="loc_mrcy_CompletedTechnologyMember_B20A1578143C90505B07747DD967B510" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TrademarksMember" xlink:label="loc_us-gaap_TrademarksMember_971C69E8E13011929475747DD9673CDA" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:to="loc_us-gaap_TrademarksMember_971C69E8E13011929475747DD9673CDA" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BacklogMember" xlink:label="loc_mrcy_BacklogMember_B82886AD182CE7B867FE747DD96754FC" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:to="loc_mrcy_BacklogMember_B82886AD182CE7B867FE747DD96754FC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_AC1FCB7C1960B870A565747DD967FB18" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_E148BA8B00BC657FAD8E747DD96770F9" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_AC1FCB7C1960B870A565747DD967FB18" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_D70513167E2B709E5121747DD9678FCA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7E6E1BF6CB9DBD85BEEC747DD967AB25" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_D70513167E2B709E5121747DD9678FCA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8D1040513EFA8678DF11747DD96753C8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7E6E1BF6CB9DBD85BEEC747DD967AB25" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8D1040513EFA8678DF11747DD96753C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_1202A45340B996B107DD747DD967C3D0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7E6E1BF6CB9DBD85BEEC747DD967AB25" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_1202A45340B996B107DD747DD967C3D0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_18DAED2C454E6D6CE8B3747DD9670226" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7E6E1BF6CB9DBD85BEEC747DD967AB25" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_18DAED2C454E6D6CE8B3747DD9670226" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/AcquiredIntangibleAssetsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/Acquisitions" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/AcquisitionsAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_928936AD213FB1BE44897DFB37F3FD96" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_928936AD213FB1BE44897DFB37F3FD96" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_76AB8B569AFE07E92EEF7DFB37F38B3E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_928936AD213FB1BE44897DFB37F3FD96" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_76AB8B569AFE07E92EEF7DFB37F38B3E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_76AB8B569AFE07E92EEF7DFB37F38B3E" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_76AB8B569AFE07E92EEF7DFB37F38B3E" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_8CD9CC290854CA37015F7DFB37F32317" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0" xlink:to="loc_mrcy_MicroneticsMember_8CD9CC290854CA37015F7DFB37F32317" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionOneMember" xlink:label="loc_mrcy_BusinessAcquisitionOneMember_33A2ED8FA6CC6A078AD27DFB37F3DD60" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0" xlink:to="loc_mrcy_BusinessAcquisitionOneMember_33A2ED8FA6CC6A078AD27DFB37F3DD60" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_LNXMember" xlink:label="loc_mrcy_LNXMember_FCF7C1FBA056B9AF3E877DFB37F3271B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_05882EB025CDE9B14ED47DFB37F3D5E0" xlink:to="loc_mrcy_LNXMember_FCF7C1FBA056B9AF3E877DFB37F3271B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_8FA04B3D2B1E4C7645BC7DFB37F394D5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_928936AD213FB1BE44897DFB37F3FD96" xlink:to="loc_us-gaap_RangeAxis_8FA04B3D2B1E4C7645BC7DFB37F394D5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_565C2B7C37418D788EC07DFB37F4865C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_8FA04B3D2B1E4C7645BC7DFB37F394D5" xlink:to="loc_us-gaap_RangeMember_565C2B7C37418D788EC07DFB37F4865C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_565C2B7C37418D788EC07DFB37F4865C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_8FA04B3D2B1E4C7645BC7DFB37F394D5" xlink:to="loc_us-gaap_RangeMember_565C2B7C37418D788EC07DFB37F4865C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_321089C335358A1EE5B27DFB37F451BA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_565C2B7C37418D788EC07DFB37F4865C" xlink:to="loc_us-gaap_MaximumMember_321089C335358A1EE5B27DFB37F451BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_E18BE8AA0FACAE07756A7DFB37F4DD30" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_928936AD213FB1BE44897DFB37F3FD96" xlink:to="loc_us-gaap_StatementScenarioAxis_E18BE8AA0FACAE07756A7DFB37F4DD30" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_FDFB4D0DC3381CD8BCB47DFB37F45D41_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_E18BE8AA0FACAE07756A7DFB37F4DD30" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_FDFB4D0DC3381CD8BCB47DFB37F45D41_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_FDFB4D0DC3381CD8BCB47DFB37F45D41" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_E18BE8AA0FACAE07756A7DFB37F4DD30" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_FDFB4D0DC3381CD8BCB47DFB37F45D41" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SellersMember" xlink:label="loc_mrcy_SellersMember_0EEB2D93435F978D0CD87DFB37F4CA0D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_FDFB4D0DC3381CD8BCB47DFB37F45D41" xlink:to="loc_mrcy_SellersMember_0EEB2D93435F978D0CD87DFB37F4CA0D" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CompanyMember" xlink:label="loc_mrcy_CompanyMember_8122D297A2C2FD3880EE7DFB37F431C9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_FDFB4D0DC3381CD8BCB47DFB37F45D41" xlink:to="loc_mrcy_CompanyMember_8122D297A2C2FD3880EE7DFB37F431C9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionSharePrice" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_40592BBCDB1263AE7FF17DFB37F42FB8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_40592BBCDB1263AE7FF17DFB37F42FB8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount_144CCFDAA762C17E5D2C7DFB37F4E120" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount_144CCFDAA762C17E5D2C7DFB37F4E120" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_B298EF7D71BB946F3B2D7DFB37F4555E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_B298EF7D71BB946F3B2D7DFB37F4555E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_38889B3FE41BA8ACC3617DFB37F44E4B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_38889B3FE41BA8ACC3617DFB37F44E4B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityCashPaid" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityCashPaid_6E60C89EE8B19D0D8BF57DFB37F48245" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityCashPaid_6E60C89EE8B19D0D8BF57DFB37F48245" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionCostOfAcquiredEntityAmountInEscrow" xlink:label="loc_mrcy_BusinessAcquisitionCostOfAcquiredEntityAmountInEscrow_20AA88F649F9D5E05EA87DFB37F4B901" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_BusinessAcquisitionCostOfAcquiredEntityAmountInEscrow_20AA88F649F9D5E05EA87DFB37F4B901" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_EscrowReleaseDate" xlink:label="loc_mrcy_EscrowReleaseDate_790D29D594A54BD162737DFB37F486F1" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_EscrowReleaseDate_790D29D594A54BD162737DFB37F486F1" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable" xlink:label="loc_mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable_E0B0E5B5243F0A6F52657DFB37F462E1" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable_E0B0E5B5243F0A6F52657DFB37F462E1" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets" xlink:label="loc_mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_6EA117A2A7B605AEAF6B7DFB37F46F02" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_6EA117A2A7B605AEAF6B7DFB37F46F02" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxAssets" xlink:label="loc_mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxAssets_A9608DF6C960986DECE07DFB37F5B677" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxAssets_A9608DF6C960986DECE07DFB37F5B677" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_16BDD62723DD2E0C4E977DFB37F58CD7" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_16BDD62723DD2E0C4E977DFB37F58CD7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionContingentConsiderationPotentialCashPayment" xlink:label="loc_us-gaap_BusinessAcquisitionContingentConsiderationPotentialCashPayment_8DF693443AC3FD252C5A7DFB37F56CF7" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessAcquisitionContingentConsiderationPotentialCashPayment_8DF693443AC3FD252C5A7DFB37F56CF7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionContingentConsiderationAtFairValue" xlink:label="loc_us-gaap_BusinessAcquisitionContingentConsiderationAtFairValue_A7D74AA7E6681795DC827DFB37F5A040" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_us-gaap_BusinessAcquisitionContingentConsiderationAtFairValue_A7D74AA7E6681795DC827DFB37F5A040" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionCostOfAcquiredEntityAmountReleasedFromEscrow" xlink:label="loc_mrcy_BusinessAcquisitionCostOfAcquiredEntityAmountReleasedFromEscrow_6AE9FD79151F4B991DA07DFB37F5C538" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_BusinessAcquisitionCostOfAcquiredEntityAmountReleasedFromEscrow_6AE9FD79151F4B991DA07DFB37F5C538" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1" xlink:label="loc_mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1_633D4BBE5A29212D7F917E73E08D7502" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_081BEABF1BAAC43E79DE7DFB37F4FC5C" xlink:to="loc_mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1_633D4BBE5A29212D7F917E73E08D7502" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/AcquisitionsNetPurchasePriceAndPreliminaryAllocationForAcquisitionDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_F1DADAA296B8ACBD8A2E7E011D95E112" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F96DE89CAE16F1E4E3747E011D95ACEC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F1DADAA296B8ACBD8A2E7E011D95E112" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F96DE89CAE16F1E4E3747E011D95ACEC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_B81626F6B4F60A6CB85E7E011D95E72E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_F96DE89CAE16F1E4E3747E011D95ACEC" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_B81626F6B4F60A6CB85E7E011D95E72E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_626B365A2B29C5B4E3457E011D957079_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_B81626F6B4F60A6CB85E7E011D95E72E" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_626B365A2B29C5B4E3457E011D957079_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_626B365A2B29C5B4E3457E011D957079" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_B81626F6B4F60A6CB85E7E011D95E72E" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_626B365A2B29C5B4E3457E011D957079" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_2CF82F0F65AC90F6B5367E011D958E00" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_626B365A2B29C5B4E3457E011D957079" xlink:to="loc_mrcy_MicroneticsMember_2CF82F0F65AC90F6B5367E011D958E00" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ConsiderationForAcquisitionAbstract" xlink:label="loc_mrcy_ConsiderationForAcquisitionAbstract_DF2A6D7BABF7DF5591997E011D95FB0B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F1DADAA296B8ACBD8A2E7E011D95E112" xlink:to="loc_mrcy_ConsiderationForAcquisitionAbstract_DF2A6D7BABF7DF5591997E011D95FB0B" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionCostOfAcquiredEntityCashPaidForSettlementOfAcquireeStockOptions" xlink:label="loc_mrcy_BusinessAcquisitionCostOfAcquiredEntityCashPaidForSettlementOfAcquireeStockOptions_C1079B585E558F230FCB7E011D96BF9A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ConsiderationForAcquisitionAbstract_DF2A6D7BABF7DF5591997E011D95FB0B" xlink:to="loc_mrcy_BusinessAcquisitionCostOfAcquiredEntityCashPaidForSettlementOfAcquireeStockOptions_C1079B585E558F230FCB7E011D96BF9A" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionFairValueOfUnvestedEmployeeShareBasedAwardsAssumed" xlink:label="loc_mrcy_BusinessAcquisitionFairValueOfUnvestedEmployeeShareBasedAwardsAssumed_97DA71843670F0AD9F7F7E011D96FB80" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ConsiderationForAcquisitionAbstract_DF2A6D7BABF7DF5591997E011D95FB0B" xlink:to="loc_mrcy_BusinessAcquisitionFairValueOfUnvestedEmployeeShareBasedAwardsAssumed_97DA71843670F0AD9F7F7E011D96FB80" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalentsAcquired" xlink:label="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalentsAcquired_E3B93C1FE82DF0BC50027E011D966F2D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ConsiderationForAcquisitionAbstract_DF2A6D7BABF7DF5591997E011D95FB0B" xlink:to="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalentsAcquired_E3B93C1FE82DF0BC50027E011D966F2D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice_C5490EAC3E74DC58143E7E011D961AD1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ConsiderationForAcquisitionAbstract_DF2A6D7BABF7DF5591997E011D95FB0B" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice_C5490EAC3E74DC58143E7E011D961AD1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_F1DADAA296B8ACBD8A2E7E011D95E112" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalents" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalents_2659785BCDB1BE8422807E011D96F710" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalents_2659785BCDB1BE8422807E011D96F710" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsReceivables" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsReceivables_FA7A3D321AEEE84A4BAD7E011D9694F9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsReceivables_FA7A3D321AEEE84A4BAD7E011D9694F9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsInventory" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsInventory_C9DFDA5DF7AE2CE849DB7E011D967E11" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsInventory_C9DFDA5DF7AE2CE849DB7E011D967E11" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationPropertyPlantAndEquipment_B5DAA5A82033249F5F437E0121AD5477" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationPropertyPlantAndEquipment_B5DAA5A82033249F5F437E0121AD5477" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionPurchasePriceAllocationDeferredTaxAsset" xlink:label="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationDeferredTaxAsset_5BCB738F6B773A9C8C7A7E011D96DEA1" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationDeferredTaxAsset_5BCB738F6B773A9C8C7A7E011D96DEA1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationOtherAssets" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationOtherAssets_4881352D04E4E89D4C0F7E011D963437" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationOtherAssets_4881352D04E4E89D4C0F7E011D963437" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionPurchasePriceAllocationAccountsPayableAndAccruedLiabilities" xlink:label="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationAccountsPayableAndAccruedLiabilities_A514F2642F7DAE8095247E011D9638B9" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationAccountsPayableAndAccruedLiabilities_A514F2642F7DAE8095247E011D9638B9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentLiabilitiesLongTermDebt" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentLiabilitiesLongTermDebt_AAE4053F54CF086835687E011D967F43" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentLiabilitiesLongTermDebt_AAE4053F54CF086835687E011D967F43" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessAcquisitionPurchasePriceAllocationDeferredTaxLiability" xlink:label="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationDeferredTaxLiability_40F8DC5B59D57976F5317E011D96C77C" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_mrcy_BusinessAcquisitionPurchasePriceAllocationDeferredTaxLiability_40F8DC5B59D57976F5317E011D96C77C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_3E588B14926C79B6EEC57E011D96E71D" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_3E588B14926C79B6EEC57E011D96E71D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationIntangibleAssetsOtherThanGoodwill_52359F0E0790DAA2ACA57E011D972D60" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationIntangibleAssetsOtherThanGoodwill_52359F0E0790DAA2ACA57E011D972D60" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount_EBFCEBE0BFDE993DC7DF7E011D975C98" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount_EBFCEBE0BFDE993DC7DF7E011D975C98" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquired" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquired_57D181CCC978C7BA1CCE7E011D97865B" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquiredLiabilitiesAssumedNetAbstract_AD95450D56C0D5C006BA7E011D96F114" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquired_57D181CCC978C7BA1CCE7E011D97865B" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/AcquisitionsSupplementalStatementsOfOperationsInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems_458510397452D55892007901A009D108" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTable" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTable_5C51302E66083D6E268D7901A009DDFA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems_458510397452D55892007901A009D108" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTable_5C51302E66083D6E268D7901A009DDFA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_4060A47A1E8DF49381E07901A0095DB3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentsTable_5C51302E66083D6E268D7901A009DDFA" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_4060A47A1E8DF49381E07901A0095DB3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AD2502EBB373ECE211F97901A0091CED_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4060A47A1E8DF49381E07901A0095DB3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AD2502EBB373ECE211F97901A0091CED_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AD2502EBB373ECE211F97901A0091CED" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4060A47A1E8DF49381E07901A0095DB3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AD2502EBB373ECE211F97901A0091CED" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_B54D27EB9FCC93D56D927901A009B6D3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_AD2502EBB373ECE211F97901A0091CED" xlink:to="loc_mrcy_MicroneticsMember_B54D27EB9FCC93D56D927901A009B6D3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_5223CAD938EF67F604837901A00A61EB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems_458510397452D55892007901A009D108" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_5223CAD938EF67F604837901A00A61EB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_7E3604E08035840899C97901A00A65C8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems_458510397452D55892007901A009D108" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_7E3604E08035840899C97901A00A65C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_D66509F55C60E8ECB4807901A00A2DEB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems_458510397452D55892007901A009D108" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_D66509F55C60E8ECB4807901A00A2DEB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_4D6B733BC3B5D23FD73B7901A00A14FD" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems_458510397452D55892007901A009D108" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_4D6B733BC3B5D23FD73B7901A00A14FD" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/AcquisitionsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/CommitmentsAndContingenciesAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermPurchaseCommitmentLineItems" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentLineItems_1B09C0FD8197FC365A2674E61224C585" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermPurchaseCommitmentTable" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentTable_C79E4C37AEAB2A187AD574E61223419C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_1B09C0FD8197FC365A2674E61224C585" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentTable_C79E4C37AEAB2A187AD574E61223419C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_07D06E7A17FD94C18AA174E61223464F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_C79E4C37AEAB2A187AD574E61223419C" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_07D06E7A17FD94C18AA174E61223464F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_8AC53CE760B4846AD9EF74E61224EE12_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_07D06E7A17FD94C18AA174E61223464F" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_8AC53CE760B4846AD9EF74E61224EE12_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_8AC53CE760B4846AD9EF74E61224EE12" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_07D06E7A17FD94C18AA174E61223464F" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_8AC53CE760B4846AD9EF74E61224EE12" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_NonCancelablePurchaseCommitmentsMember" xlink:label="loc_mrcy_NonCancelablePurchaseCommitmentsMember_61828A92F668C87CD35C74E612243EBA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_8AC53CE760B4846AD9EF74E61224EE12" xlink:to="loc_mrcy_NonCancelablePurchaseCommitmentsMember_61828A92F668C87CD35C74E612243EBA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SignificantPurchaseCommitmentRemainingMinimumAmountCommitted" xlink:label="loc_us-gaap_SignificantPurchaseCommitmentRemainingMinimumAmountCommitted_9D00006157B60E3DE3C174E612240E82" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_1B09C0FD8197FC365A2674E61224C585" xlink:to="loc_us-gaap_SignificantPurchaseCommitmentRemainingMinimumAmountCommitted_9D00006157B60E3DE3C174E612240E82" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet" xlink:label="loc_us-gaap_OperatingLeasesRentExpenseNet_C4EED9681C56305BA9AE74E61224AA34" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_1B09C0FD8197FC365A2674E61224C585" xlink:to="loc_us-gaap_OperatingLeasesRentExpenseNet_C4EED9681C56305BA9AE74E61224AA34" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/CommitmentsAndContingenciesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/ComponentsOfIncomeBeforeIncomeTaxesAndIncomeTaxExpenseBenefitDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/ComponentsOfNetDeferredTaxAssetsLiabilitiesDetail" xlink:type="extended">
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ScheduleOfComponentsOfDeferredTaxProvisionLineItems" xlink:label="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionLineItems_50485B5CA16B56AB4C3074B89F10EE9F" xlink:type="locator" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ScheduleOfComponentsOfDeferredTaxProvisionTable" xlink:label="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionTable_64E9746324CC79959E0C74B89F0F120F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionLineItems_50485B5CA16B56AB4C3074B89F10EE9F" xlink:to="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionTable_64E9746324CC79959E0C74B89F0F120F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_DeferredTaxAssetsAndLiabilitiesAxis" xlink:label="loc_mrcy_DeferredTaxAssetsAndLiabilitiesAxis_01077D413643F983B6F574B89F0F4D72" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionTable_64E9746324CC79959E0C74B89F0F120F" xlink:to="loc_mrcy_DeferredTaxAssetsAndLiabilitiesAxis_01077D413643F983B6F574B89F0F4D72" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_DeferredTaxAssetsAndLiabilitiesDomain" xlink:label="loc_mrcy_DeferredTaxAssetsAndLiabilitiesDomain_09C3C2F0DF68BA84BB2974B89F0FAF58_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_mrcy_DeferredTaxAssetsAndLiabilitiesAxis_01077D413643F983B6F574B89F0F4D72" xlink:to="loc_mrcy_DeferredTaxAssetsAndLiabilitiesDomain_09C3C2F0DF68BA84BB2974B89F0FAF58_default" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_DeferredTaxAssetsAndLiabilitiesDomain" xlink:label="loc_mrcy_DeferredTaxAssetsAndLiabilitiesDomain_09C3C2F0DF68BA84BB2974B89F0FAF58" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_mrcy_DeferredTaxAssetsAndLiabilitiesAxis_01077D413643F983B6F574B89F0F4D72" xlink:to="loc_mrcy_DeferredTaxAssetsAndLiabilitiesDomain_09C3C2F0DF68BA84BB2974B89F0FAF58" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_OtherAmortizableAssetsMember" xlink:label="loc_mrcy_OtherAmortizableAssetsMember_56AA0FCCA09F4BF74F5C74B89F0FB2C3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_DeferredTaxAssetsAndLiabilitiesDomain_09C3C2F0DF68BA84BB2974B89F0FAF58" xlink:to="loc_mrcy_OtherAmortizableAssetsMember_56AA0FCCA09F4BF74F5C74B89F0FB2C3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsNetAbstract" xlink:label="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionLineItems_50485B5CA16B56AB4C3074B89F10EE9F" xlink:to="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_DeferredTaxAssetsInventoryValuationAndReceivableAllowances" xlink:label="loc_mrcy_DeferredTaxAssetsInventoryValuationAndReceivableAllowances_55826100AFB0F060C5F274B89F105FA6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_mrcy_DeferredTaxAssetsInventoryValuationAndReceivableAllowances_55826100AFB0F060C5F274B89F105FA6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_68159A3618D6E1089B4174B89F104B56" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_68159A3618D6E1089B4174B89F104B56" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_6C5A05B4F7399B3854E974B89F10FF19" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_6C5A05B4F7399B3854E974B89F10FF19" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_0BAB65BD225832AAB18F74B89F101469" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_0BAB65BD225832AAB18F74B89F101469" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsDeferredGainOnSaleLeasebackTransaction" xlink:label="loc_us-gaap_DeferredTaxAssetsDeferredGainOnSaleLeasebackTransaction_7B70E34DBCD1A763203A74B89F10CA75" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsDeferredGainOnSaleLeasebackTransaction_7B70E34DBCD1A763203A74B89F10CA75" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_1BF02A31312E5C38E99274B89F10D694" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_1BF02A31312E5C38E99274B89F10D694" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_9E0E87FA54BCE3E1778B74B89F103BE3" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_9E0E87FA54BCE3E1778B74B89F103BE3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_F61514BE02355CB4871774B89F10BA52" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_F61514BE02355CB4871774B89F10BA52" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_77B9F898545E421BB1C874B89F10DE3A" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_77B9F898545E421BB1C874B89F10DE3A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_8E68E5513C0BE019BCDA74B89F103143" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_5D7AB87BCDD72DFBA76774B89F103937" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_8E68E5513C0BE019BCDA74B89F103143" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesAbstract" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionLineItems_50485B5CA16B56AB4C3074B89F10EE9F" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome_F383212D446B739E62F874B89F109152" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome_F383212D446B739E62F874B89F109152" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_FB0167A6F4FA943F1A7B74B89F10AEE1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_FB0167A6F4FA943F1A7B74B89F10AEE1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_143DD2920DC434C14F1874B89F10EA59" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_143DD2920DC434C14F1874B89F10EA59" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesOther" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther_57217A7EC167FDB794B674CD9950847F" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesOther_57217A7EC167FDB794B674CD9950847F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_us-gaap_DeferredTaxLiabilities_C2F21EC5752B70C7E5D274B89F1057B3" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesAbstract_565ED542B5C8485A201174B89F109958" xlink:to="loc_us-gaap_DeferredTaxLiabilities_C2F21EC5752B70C7E5D274B89F1057B3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_372AE8610EDC6DE8803174B89F107942" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ScheduleOfComponentsOfDeferredTaxProvisionLineItems_50485B5CA16B56AB4C3074B89F10EE9F" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_372AE8610EDC6DE8803174B89F107942" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/ConsolidatedBalanceSheets" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_E83D22031538B6E4539782FD631DFDF0" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_D041A26413855AC5337082FD631D7071" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_E83D22031538B6E4539782FD631DFDF0" xlink:to="loc_us-gaap_StatementTable_D041A26413855AC5337082FD631D7071" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_AA4F2B756DA7442E4EB282FD631D29A7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_D041A26413855AC5337082FD631D7071" xlink:to="loc_dei_LegalEntityAxis_AA4F2B756DA7442E4EB282FD631D29A7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_22453690FF4035F9B43282FD631D2ABD_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_AA4F2B756DA7442E4EB282FD631D29A7" xlink:to="loc_dei_EntityDomain_22453690FF4035F9B43282FD631D2ABD_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_22453690FF4035F9B43282FD631D2ABD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_AA4F2B756DA7442E4EB282FD631D29A7" xlink:to="loc_dei_EntityDomain_22453690FF4035F9B43282FD631D2ABD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E83D22031538B6E4539782FD631DFDF0" xlink:to="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_F52B4000A13382CC522C82FD631E8614" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_F52B4000A13382CC522C82FD631E8614" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_92649A311E11AEACDD4582FD631E65B3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_92649A311E11AEACDD4582FD631E65B3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" xlink:label="loc_us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear_59C0FBBDA3B3D1909E3C82FD631FCF3F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear_59C0FBBDA3B3D1909E3C82FD631FCF3F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_F56810E508941493F17182FD631F30B7" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_InventoryNet_F56810E508941493F17182FD631F30B7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxAssetsNetCurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsNetCurrent_759E57818CDD8AB34D8682FD631F12C8" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_DeferredTaxAssetsNetCurrent_759E57818CDD8AB34D8682FD631F12C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PrepaidTaxes" xlink:label="loc_us-gaap_PrepaidTaxes_4E1FC9BE9EE0A4821EAD82FD631FEDC4" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_PrepaidTaxes_4E1FC9BE9EE0A4821EAD82FD631FEDC4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_B90B8108CB863ECA015282FD631F5E6C" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_B90B8108CB863ECA015282FD631F5E6C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_534F9189E3D95CF8190482FD631F5428" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_7E05135AF57AB095D7A182FD631D201A" xlink:to="loc_us-gaap_AssetsCurrent_534F9189E3D95CF8190482FD631F5428" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_A7352380FF5B1FA3172382FD631F22EC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_A7352380FF5B1FA3172382FD631F22EC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_4931CF369F44BCA30B3582FD631FC165" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_4931CF369F44BCA30B3582FD631FC165" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_9AD45141F849A374C93C82FD631FD26D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_Goodwill_9AD45141F849A374C93C82FD631FD26D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_35597220C8A49C8FC63882FD631F62B0" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_35597220C8A49C8FC63882FD631F62B0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_DAF253BA5B51002C2A8D82FD631FE68F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_DAF253BA5B51002C2A8D82FD631FE68F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_74A0966F43E7B57AF6A282FD631FD01D" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9152C6849ED7E58F503482FD631DC85A" xlink:to="loc_us-gaap_Assets_74A0966F43E7B57AF6A282FD631FD01D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E83D22031538B6E4539782FD631DFDF0" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_06357D4AA57063E8DB6882FD63200CC6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:to="loc_us-gaap_AccountsPayableCurrent_06357D4AA57063E8DB6882FD63200CC6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_612E6E6385F803F1DE7D82FD63201DD0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_612E6E6385F803F1DE7D82FD63201DD0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_1BE7D4FB88A421773D8082FD63203157" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_1BE7D4FB88A421773D8082FD63203157" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="loc_us-gaap_DeferredRevenueCurrent_B230ED9728FCB3F108A782FD6320488B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:to="loc_us-gaap_DeferredRevenueCurrent_B230ED9728FCB3F108A782FD6320488B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_ACF1B1AC61671279DE5582FD63200738" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_12DF9793A9A9D9796F3482FD6320E8A6" xlink:to="loc_us-gaap_LiabilitiesCurrent_ACF1B1AC61671279DE5582FD63200738" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SaleLeasebackTransactionDeferredGainNet" xlink:label="loc_us-gaap_SaleLeasebackTransactionDeferredGainNet_57296603CF94E2DD475C82FD632056EE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_SaleLeasebackTransactionDeferredGainNet_57296603CF94E2DD475C82FD632056EE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_7C6D77747CD15AAE357182FD6320A542" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_7C6D77747CD15AAE357182FD6320A542" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccruedIncomeTaxesNoncurrent" xlink:label="loc_us-gaap_AccruedIncomeTaxesNoncurrent_404FD6CC44ED3943D7D582FD63206589" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_AccruedIncomeTaxesNoncurrent_404FD6CC44ED3943D7D582FD63206589" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_446F0902A3DD6D66F97F82FD63206D51" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_446F0902A3DD6D66F97F82FD63206D51" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_5CBDB72DA3673F246D2982FD63206D45" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_Liabilities_5CBDB72DA3673F246D2982FD63206D45" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_30714C4A0A4C4EC0752482FD63204643" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_CommitmentsAndContingencies_30714C4A0A4C4EC0752482FD63204643" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_67AA0622F77A1B15F42B82FD63206F4E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:to="loc_us-gaap_PreferredStockValue_67AA0622F77A1B15F42B82FD63206F4E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_B812938712D7C6AA66F182FD6321CF2A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:to="loc_us-gaap_CommonStockValue_B812938712D7C6AA66F182FD6321CF2A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaap_AdditionalPaidInCapital_61B05D7D2671752C1A4E82FD63265805" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:to="loc_us-gaap_AdditionalPaidInCapital_61B05D7D2671752C1A4E82FD63265805" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_2E524BB2B5144B82800D82FD63260C38" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_2E524BB2B5144B82800D82FD63260C38" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_3A356B8831983EC822BD82FD63268175" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_3A356B8831983EC822BD82FD63268175" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_F78B6A493E623088504A82FD63267BE0" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_A336A11BA16033987CA482FD6320183F" xlink:to="loc_us-gaap_StockholdersEquity_F78B6A493E623088504A82FD63267BE0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_721447F00F955F2D230D82FD632668CC" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_DEDD4EE0E799FFF1CA2082FD6320A585" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_721447F00F955F2D230D82FD632668CC" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_2359C9717782D855C3DB72FFC528D2A4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_StatementTable_2359C9717782D855C3DB72FFC528D2A4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_F8F768E8C5E6C56CF42372FFC52803A8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2359C9717782D855C3DB72FFC528D2A4" xlink:to="loc_dei_LegalEntityAxis_F8F768E8C5E6C56CF42372FFC52803A8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_73381E8D48F16697E4FD72FFC52819EE_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_F8F768E8C5E6C56CF42372FFC52803A8" xlink:to="loc_dei_EntityDomain_73381E8D48F16697E4FD72FFC52819EE_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_73381E8D48F16697E4FD72FFC52819EE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_F8F768E8C5E6C56CF42372FFC52803A8" xlink:to="loc_dei_EntityDomain_73381E8D48F16697E4FD72FFC52819EE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_DC70C0EF9C6EC498916172FFC528943F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_DC70C0EF9C6EC498916172FFC528943F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_5B7193D09B1620D60B6372FFC5286F13" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_5B7193D09B1620D60B6372FFC5286F13" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_E0D80EC0C4BCB8F155EC72FFC52978D4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_E0D80EC0C4BCB8F155EC72FFC52978D4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_41982595AC75BB3A394972FFC529153C" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_PreferredStockSharesIssued_41982595AC75BB3A394972FFC529153C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_81F60B7B972AFCD4DDE772FFC529C8CA" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_81F60B7B972AFCD4DDE772FFC529C8CA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_05BA99F470C3705AB41C72FFC52958F4" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_05BA99F470C3705AB41C72FFC52958F4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_509A179655C1FC98EF3272FFC529516D" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_509A179655C1FC98EF3272FFC529516D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_65F04526B660D47A3F1A72FFC52958BE" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_CommonStockSharesIssued_65F04526B660D47A3F1A72FFC52958BE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_93092D0168252611E88672FFC52976E3" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D72083AF54A8F90FA3D672FFC528AAF8" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_93092D0168252611E88672FFC52976E3" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_6B310F045E96927E8DAA82FDA3E669BB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_StatementTable_6B310F045E96927E8DAA82FDA3E669BB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_7F34E1EA67A1653F63FF82FDA3E647CE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_6B310F045E96927E8DAA82FDA3E669BB" xlink:to="loc_dei_LegalEntityAxis_7F34E1EA67A1653F63FF82FDA3E647CE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_A74112D80E16115C066382FDA3E60AD2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_7F34E1EA67A1653F63FF82FDA3E647CE" xlink:to="loc_dei_EntityDomain_A74112D80E16115C066382FDA3E60AD2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_A74112D80E16115C066382FDA3E60AD2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_7F34E1EA67A1653F63FF82FDA3E647CE" xlink:to="loc_dei_EntityDomain_A74112D80E16115C066382FDA3E60AD2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_770D9CCF473C899383B482FDA3E6B263" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_770D9CCF473C899383B482FDA3E6B263" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_8DD6441865EACD4B01A682FDA3E7E400" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_770D9CCF473C899383B482FDA3E6B263" xlink:to="loc_us-gaap_NetIncomeLoss_8DD6441865EACD4B01A682FDA3E7E400" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_770D9CCF473C899383B482FDA3E6B263" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_54F5D29D411201A0F05082FDA3E7B30D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_54F5D29D411201A0F05082FDA3E7B30D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_0E3483AF68ECD5E7351882FDA3E7BDF3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_ShareBasedCompensation_0E3483AF68ECD5E7351882FDA3E7BDF3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_8EE472E78DE66333BED982FDA3E74CBF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_8EE472E78DE66333BED982FDA3E74CBF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4B740CCB7F8EAC42567682FDA3E77AA8" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4B740CCB7F8EAC42567682FDA3E77AA8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_D843871DF64131E5375782FDA3E7940C" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_D843871DF64131E5375782FDA3E7940C" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1" xlink:label="loc_mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1_D9A142AAFF50DD43F4E082FDA3E754DC" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1_D9A142AAFF50DD43F4E082FDA3E754DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_72C0DDD5877A3963B10882FDA3E7677F" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_72C0DDD5877A3963B10882FDA3E7677F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_CF26E94D4FCC313072FD82FDA3E71BC3" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_CF26E94D4FCC313072FD82FDA3E71BC3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_356730A5E572827CF3E082FDA3E7963E" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_907A03145FCF7F55F00F82FDA3E7004F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_907A03145FCF7F55F00F82FDA3E7004F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_5050004BEC84F35807BA82FDA3E7A0A5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_5050004BEC84F35807BA82FDA3E7A0A5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidTaxes" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidTaxes_A62A1C191DBC50CE74FC82FDA3E754BB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidTaxes_A62A1C191DBC50CE74FC82FDA3E754BB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidExpense_757AF84F6C8EA90CF26482FDA3E70DA9" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidExpense_757AF84F6C8EA90CF26482FDA3E70DA9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_0FEE51DF0AAEB1985AB482FDA3E850EC" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_0FEE51DF0AAEB1985AB482FDA3E850EC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_ED92433634819D0E0AEF82FDA3E8F72F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_ED92433634819D0E0AEF82FDA3E8F72F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenueAndCustomerAdvancesAndDeposits" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredRevenueAndCustomerAdvancesAndDeposits_E6AFFBE43B1AB29EDC4B82FDA3E8CB1D" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredRevenueAndCustomerAdvancesAndDeposits_E6AFFBE43B1AB29EDC4B82FDA3E8CB1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_A640F9A2AF513EE964EA82FDA3E8F730" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_A640F9A2AF513EE964EA82FDA3E8F730" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_BBC6905A03A2C8E9F60982FDA3E85484" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_60777332EB8F766AE56682FDA3E7E9BF" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_BBC6905A03A2C8E9F60982FDA3E85484" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1D2260D2BDF629D30A6D82FDA3E82745" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_770D9CCF473C899383B482FDA3E6B263" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1D2260D2BDF629D30A6D82FDA3E82745" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_46C8D6A4426849F36FFB82FDA3E8078B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_46C8D6A4426849F36FFB82FDA3E8078B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities" xlink:label="loc_us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities_F1FEC9CD08A88DF92D5782FDA3E8E61A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities_F1FEC9CD08A88DF92D5782FDA3E8E61A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_E2E4C0263A2CCCFEA47B82FDA3E8F874" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_E2E4C0263A2CCCFEA47B82FDA3E8F874" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_E62CE1AD2BD82D6BC8F082FDA3E83319" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_E62CE1AD2BD82D6BC8F082FDA3E83319" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_D7D82AB4B4C82EFCAA9082FDA3E8F5EE" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_D7D82AB4B4C82EFCAA9082FDA3E8F5EE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_3AAB335F7C6A0766665182FDA3E85517" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_3AAB335F7C6A0766665182FDA3E85517" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_49AB6D5E85EEDB99619B82FDA3E831BF" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_213C1FCDC446E9E3D00582FDA3E8D14F" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_49AB6D5E85EEDB99619B82FDA3E831BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_DA1769827267F46912D782FDA3E98E78" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_DA1769827267F46912D782FDA3E98E78" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_F7A9F3C20786DC76B60A82FDA3E91BF5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_F7A9F3C20786DC76B60A82FDA3E91BF5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_7DBBE084589D1FF1155E82FDA3E9DB06" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_7DBBE084589D1FF1155E82FDA3E9DB06" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_D1B65B7DD9E48B5BA2D782FDA3E9C0F1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_D1B65B7DD9E48B5BA2D782FDA3E9C0F1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_51DD20206259A1EACC6E82FDA3E96072" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_51DD20206259A1EACC6E82FDA3E96072" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_0C065BD1F83A213D63A982FDA3E982A5" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_0C065BD1F83A213D63A982FDA3E982A5" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_IncreaseDecreaseinRestrictedCashFinancingActivities" xlink:label="loc_mrcy_IncreaseDecreaseinRestrictedCashFinancingActivities_0F9F31DD08CF7AD132CC82FDA3E9AFFC" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_mrcy_IncreaseDecreaseinRestrictedCashFinancingActivities_0F9F31DD08CF7AD132CC82FDA3E9AFFC" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ProceedsFromRepaymentsOfDebtAndCapitalLeaseObligations" xlink:label="loc_mrcy_ProceedsFromRepaymentsOfDebtAndCapitalLeaseObligations_E7E3AD3636C5C7F9C1FB82FDA3E99403" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_mrcy_ProceedsFromRepaymentsOfDebtAndCapitalLeaseObligations_E7E3AD3636C5C7F9C1FB82FDA3E99403" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_0EB4D1BA0717AAE10FA082FDA3E9B01B" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_B82147B32F3422B9F0A982FDA3E841C6" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_0EB4D1BA0717AAE10FA082FDA3E9B01B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_4307DCC322DF40A6E04282FDA3E924FA" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_4307DCC322DF40A6E04282FDA3E924FA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_584C8F054D528A6DCE4682FDA3E97488" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_584C8F054D528A6DCE4682FDA3E97488" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_7C4D4A4AB99D40D397F482FDA3E90327" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_7C4D4A4AB99D40D397F482FDA3E90327" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_CF8EF4C997B984F2A19982FDA3E99930" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_CF8EF4C997B984F2A19982FDA3E99930" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_5853CCFEA4F9C15E13D782FDA3E9FC28" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_CF8EF4C997B984F2A19982FDA3E99930" xlink:to="loc_us-gaap_InterestPaid_5853CCFEA4F9C15E13D782FDA3E9FC28" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_198DBF400F4D43E98AE082FDA3E91D19" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_CF8EF4C997B984F2A19982FDA3E99930" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_198DBF400F4D43E98AE082FDA3E91D19" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_C803BD3A2E596AA6557982FDA3EA1BA8" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2F9A242251E75056282F82FDA3E6B740" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_C803BD3A2E596AA6557982FDA3EA1BA8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssued1" xlink:label="loc_us-gaap_StockIssued1_EA76813D3161AC4AFB6782FDA3EAA39B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_C803BD3A2E596AA6557982FDA3EA1BA8" xlink:to="loc_us-gaap_StockIssued1_EA76813D3161AC4AFB6782FDA3EAA39B" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ShareBasedCompensationStockOptionsAssumed" xlink:label="loc_mrcy_ShareBasedCompensationStockOptionsAssumed_FC54BA5FDA383E00C0A782FDA3EAC158" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_C803BD3A2E596AA6557982FDA3EA1BA8" xlink:to="loc_mrcy_ShareBasedCompensationStockOptionsAssumed_FC54BA5FDA383E00C0A782FDA3EAC158" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionIntangibleAssetsAcquired1" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionIntangibleAssetsAcquired1_9099A61E7200C3A92C2482FDA3EAFE51" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_C803BD3A2E596AA6557982FDA3EA1BA8" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionIntangibleAssetsAcquired1_9099A61E7200C3A92C2482FDA3EAFE51" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CapitalLeaseObligationsIncurred" xlink:label="loc_us-gaap_CapitalLeaseObligationsIncurred_092791386E8ACAA9726B82FDA3EA4721" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_C803BD3A2E596AA6557982FDA3EA1BA8" xlink:to="loc_us-gaap_CapitalLeaseObligationsIncurred_092791386E8ACAA9726B82FDA3EA4721" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveIncomeLoss" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_07688B89F3EBE23932DF7DFB385450B0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_StatementTable_07688B89F3EBE23932DF7DFB385450B0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_36381138B696AA9F56417DFB38546528" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_07688B89F3EBE23932DF7DFB385450B0" xlink:to="loc_dei_LegalEntityAxis_36381138B696AA9F56417DFB38546528" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_BA2D2FE17AA7DFABC90A7DFB385447D0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_36381138B696AA9F56417DFB38546528" xlink:to="loc_dei_EntityDomain_BA2D2FE17AA7DFABC90A7DFB385447D0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_BA2D2FE17AA7DFABC90A7DFB385447D0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_36381138B696AA9F56417DFB38546528" xlink:to="loc_dei_EntityDomain_BA2D2FE17AA7DFABC90A7DFB385447D0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_AD0A9C50B57768FB7C2F7DFB3855BAA0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_Revenues_AD0A9C50B57768FB7C2F7DFB3855BAA0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_89399F605D0F9D9E490D7DFB3855E650" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_CostOfRevenue_89399F605D0F9D9E490D7DFB3855E650" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_143C3196308EDDE85E537DFB385559B0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_GrossProfit_143C3196308EDDE85E537DFB385559B0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_8A74A7814529206489007DFB3855CF2F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_8A74A7814529206489007DFB3855CF2F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_4BA5BDA8A1E0E3C0B9F17DFB3855B062" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_4BA5BDA8A1E0E3C0B9F17DFB3855B062" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_988B2A38EBC77D3560577DFB38551B6D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_988B2A38EBC77D3560577DFB38551B6D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_E19346369D15F05C49F07DFB38556762" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_RestructuringCharges_E19346369D15F05C49F07DFB38556762" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_16D4DE0417BC275CC7887DFB3855DD9E" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_16D4DE0417BC275CC7887DFB3855DD9E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_BBD7B8A7294F96E9EE0F7DFB3855A223" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_BBD7B8A7294F96E9EE0F7DFB3855A223" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1" xlink:label="loc_mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1_A256036D73CAB1F799B07E647DD07E4A" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_mrcy_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsiderationLiability1_A256036D73CAB1F799B07E647DD07E4A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_11D995685CE0BDF360C47DFB38558020" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8CF4004D35E83ABE68DB7DFB3855952B" xlink:to="loc_us-gaap_OperatingExpenses_11D995685CE0BDF360C47DFB38558020" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_6816D83A032FB08E8D427DFB3855309B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_OperatingIncomeLoss_6816D83A032FB08E8D427DFB3855309B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaap_InvestmentIncomeInterest_C4A7A2D56E693B6E25E87DFB385675EA" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_InvestmentIncomeInterest_C4A7A2D56E693B6E25E87DFB385675EA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_0D7FAFC80F0D002440A77DFB38566BDA" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_InterestExpense_0D7FAFC80F0D002440A77DFB38566BDA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_B260E190DD1428D5737D7DFB38560266" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_B260E190DD1428D5737D7DFB38560266" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_A056CEFF99141B36B9407DFB385681C4" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_A056CEFF99141B36B9407DFB385681C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_2EFEA82BFF74163877ED7DFB3856D234" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_2EFEA82BFF74163877ED7DFB3856D234" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_AF0F30593C43AF1E3CDD7DFB38566C6F" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_NetIncomeLoss_AF0F30593C43AF1E3CDD7DFB38566C6F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EarningsPerShareBasicAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_48470D028826DCB2041B7DFB3856E8D8" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_48470D028826DCB2041B7DFB3856E8D8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_33A665D5BFD17E8B7A757DFB38565A97" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_48470D028826DCB2041B7DFB3856E8D8" xlink:to="loc_us-gaap_EarningsPerShareBasic_33A665D5BFD17E8B7A757DFB38565A97" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EarningsPerShareDilutedAbstract" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_FC25FD20A2F223D68FBD7DFB3856F200" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_FC25FD20A2F223D68FBD7DFB3856F200" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_BA55DF31B42610EE669F7DFB3856FD15" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_FC25FD20A2F223D68FBD7DFB3856F200" xlink:to="loc_us-gaap_EarningsPerShareDiluted_BA55DF31B42610EE669F7DFB3856FD15" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_WeightedAverageNumberBasicAndDilutedSharesOutstandingAbstract" xlink:label="loc_mrcy_WeightedAverageNumberBasicAndDilutedSharesOutstandingAbstract_5CC23BA9F5F192308C7D7DFB385635BF" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_mrcy_WeightedAverageNumberBasicAndDilutedSharesOutstandingAbstract_5CC23BA9F5F192308C7D7DFB385635BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_AD41D40E91A7C7BD0E727DFB38563C93" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_WeightedAverageNumberBasicAndDilutedSharesOutstandingAbstract_5CC23BA9F5F192308C7D7DFB385635BF" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_AD41D40E91A7C7BD0E727DFB38563C93" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_1D14F7DDB0BBD933C1187DFB38568951" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_WeightedAverageNumberBasicAndDilutedSharesOutstandingAbstract_5CC23BA9F5F192308C7D7DFB385635BF" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_1D14F7DDB0BBD933C1187DFB38568951" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAbstract" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_AA24AE3FBA936CDC69AE7DFB3856DC95" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7B70B2461B1E6AFBF8907DFB385513BC" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_AA24AE3FBA936CDC69AE7DFB3856DC95" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_39A628C6A15EF23AF4647DFB3857F0E3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_AA24AE3FBA936CDC69AE7DFB3856DC95" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_39A628C6A15EF23AF4647DFB3857F0E3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_21A80E7B541DDED208037DFB38577265" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_AA24AE3FBA936CDC69AE7DFB3856DC95" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_21A80E7B541DDED208037DFB38577265" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_278DB74B4354B037DE497DFB3857FE84" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_AA24AE3FBA936CDC69AE7DFB3856DC95" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_278DB74B4354B037DE497DFB3857FE84" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/ConsolidatedStatementsOfShareholdersEquity" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_F4BE3B76442D3FEB70CD7EF9CDCF9228" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_BE9E460DEA4D2A2565227EF9CDCE1783" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_F4BE3B76442D3FEB70CD7EF9CDCF9228" xlink:to="loc_us-gaap_StatementTable_BE9E460DEA4D2A2565227EF9CDCE1783" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_CE4F979BF7D5EFA86D8B7EF9CDCEA32B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_BE9E460DEA4D2A2565227EF9CDCE1783" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_CE4F979BF7D5EFA86D8B7EF9CDCEA32B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_CE4F979BF7D5EFA86D8B7EF9CDCEA32B" xlink:to="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_CE4F979BF7D5EFA86D8B7EF9CDCEA32B" xlink:to="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_A84726E9F6AD290C6BC47EF9CDCE630C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6" xlink:to="loc_us-gaap_CommonStockMember_A84726E9F6AD290C6BC47EF9CDCE630C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_7F4F5465F85CF3ABCFFD7EF9CDCE8090" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_7F4F5465F85CF3ABCFFD7EF9CDCE8090" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_622C41500EB7806BDB2A7EF9CDCE449C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6" xlink:to="loc_us-gaap_RetainedEarningsMember_622C41500EB7806BDB2A7EF9CDCE449C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F1C66636FD6C88E2D1817EF9CDCE366A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5E9E52D4F7C44D093D127EF9CDCE96A6" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F1C66636FD6C88E2D1817EF9CDCE366A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F4BE3B76442D3FEB70CD7EF9CDCF9228" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_0C2757F6840CF8D3D45A7EF9CDCFB709" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_0C2757F6840CF8D3D45A7EF9CDCFB709" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_74A3502990017580DF617EF9CDCF6403" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockholdersEquity_74A3502990017580DF617EF9CDCF6403" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_95749E12FCA50FFCEEF07EF9CDCFA6C0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_95749E12FCA50FFCEEF07EF9CDCFA6C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_DE5C3FD810FF722D8BE67EF9CDCFE69D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_DE5C3FD810FF722D8BE67EF9CDCFE69D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_59ED3BF986B73CD018067EF9CDCF7D5B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_59ED3BF986B73CD018067EF9CDCF7D5B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_907EADCECC1F54D476517EF9CDCF13B1" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_907EADCECC1F54D476517EF9CDCF13B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_1D6BC515EA96C8ADC6C37EF9CDD40CFF" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_1D6BC515EA96C8ADC6C37EF9CDD40CFF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_9FE40AD1CAC3424326937EF9CDD46C3D" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_9FE40AD1CAC3424326937EF9CDD46C3D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_B26CDFC792154BE139AD7EF9CDD4BAAB" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_B26CDFC792154BE139AD7EF9CDD4BAAB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation_AAF2E26273BF24B8B6DF7EF9CDD4F0EC" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation_AAF2E26273BF24B8B6DF7EF9CDD4F0EC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_8B92C276168A0EFACF0E7EF9CDD54808" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_NetIncomeLoss_8B92C276168A0EFACF0E7EF9CDD54808" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AdjustmentstoAdditionalPaidinCapitalSharebasedCompensationOptionsAssumedInAcquistion" xlink:label="loc_mrcy_AdjustmentstoAdditionalPaidinCapitalSharebasedCompensationOptionsAssumedInAcquistion_10353A4AD84FD5992C9F7F0FC103BF23" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_mrcy_AdjustmentstoAdditionalPaidinCapitalSharebasedCompensationOptionsAssumedInAcquistion_10353A4AD84FD5992C9F7F0FC103BF23" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_E32A836F9C36626F0D0E7EF9CDD58BEF" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_E32A836F9C36626F0D0E7EF9CDD58BEF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_177EF8A35CC191CA89347EF9CDD56E22" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_AE1EA3881F625A73731A7EF9CDCF43EB" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_177EF8A35CC191CA89347EF9CDD56E22" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/Debt" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/DebtAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_E67F13E8623ADE7630C27DFB375A7994" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_E67F13E8623ADE7630C27DFB375A7994" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_24893D1C6F4ACCD1DC427DFB375A9938_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_E67F13E8623ADE7630C27DFB375A7994" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_24893D1C6F4ACCD1DC427DFB375A9938_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_24893D1C6F4ACCD1DC427DFB375A9938" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_E67F13E8623ADE7630C27DFB375A7994" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_24893D1C6F4ACCD1DC427DFB375A9938" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_KeyBankNationalAssociationMember" xlink:label="loc_mrcy_KeyBankNationalAssociationMember_20AF509F65ECC95D7BE87DFB375A5C08" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_24893D1C6F4ACCD1DC427DFB375A9938" xlink:to="loc_mrcy_KeyBankNationalAssociationMember_20AF509F65ECC95D7BE87DFB375A5C08" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_CFE0E2EFB82663C560977DFB375ABDEA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:to="loc_us-gaap_DebtInstrumentAxis_CFE0E2EFB82663C560977DFB375ABDEA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_F10888A1EC97C724EB8B7DFB375A871B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_CFE0E2EFB82663C560977DFB375ABDEA" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_F10888A1EC97C724EB8B7DFB375A871B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_F10888A1EC97C724EB8B7DFB375A871B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_CFE0E2EFB82663C560977DFB375ABDEA" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_F10888A1EC97C724EB8B7DFB375A871B" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SiliconValleyBankLoanAndSecurityAgreementMember" xlink:label="loc_mrcy_SiliconValleyBankLoanAndSecurityAgreementMember_6F9F3E4284F51D33E5857DFB375B3C9D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_F10888A1EC97C724EB8B7DFB375A871B" xlink:to="loc_mrcy_SiliconValleyBankLoanAndSecurityAgreementMember_6F9F3E4284F51D33E5857DFB375B3C9D" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AmendedLoanAgreementMember" xlink:label="loc_mrcy_AmendedLoanAgreementMember_F21D652A55A5F6328DE37DFB375B545B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_F10888A1EC97C724EB8B7DFB375A871B" xlink:to="loc_mrcy_AmendedLoanAgreementMember_F21D652A55A5F6328DE37DFB375B545B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_709DFBC12AA22E066AC37DFB375BAE2E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_709DFBC12AA22E066AC37DFB375BAE2E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_709DFBC12AA22E066AC37DFB375BAE2E" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_709DFBC12AA22E066AC37DFB375BAE2E" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SeniorUnsecuredCreditFacilitiesMember" xlink:label="loc_mrcy_SeniorUnsecuredCreditFacilitiesMember_45BFC8C59D25480DE9357DFB375BF77F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:to="loc_mrcy_SeniorUnsecuredCreditFacilitiesMember_45BFC8C59D25480DE9357DFB375BF77F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_C88CC2EA6BE60A0A7C897DFB375B7D11" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:to="loc_us-gaap_LineOfCreditMember_C88CC2EA6BE60A0A7C897DFB375B7D11" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AcquisitionLineMember" xlink:label="loc_mrcy_AcquisitionLineMember_6799137E2E510672C19B7DFB375B191C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:to="loc_mrcy_AcquisitionLineMember_6799137E2E510672C19B7DFB375B191C" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ForeignSubsidiariesMember" xlink:label="loc_mrcy_ForeignSubsidiariesMember_219FF3E01A7AD2B8A0267DFB375B02D4" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:to="loc_mrcy_ForeignSubsidiariesMember_219FF3E01A7AD2B8A0267DFB375B02D4" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SeniorSecuredCreditFacilityMember" xlink:label="loc_mrcy_SeniorSecuredCreditFacilityMember_FC9310CC50AC13C361267DFB375B9AAD" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2708390399BF514CCB2A7DFB375B40B7" xlink:to="loc_mrcy_SeniorSecuredCreditFacilityMember_FC9310CC50AC13C361267DFB375B9AAD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_3016EF5CE44B27C832757DFB375B0A72" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:to="loc_us-gaap_RangeAxis_3016EF5CE44B27C832757DFB375B0A72" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_32DF7702E72443774A457DFB375B824C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_3016EF5CE44B27C832757DFB375B0A72" xlink:to="loc_us-gaap_RangeMember_32DF7702E72443774A457DFB375B824C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_32DF7702E72443774A457DFB375B824C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_3016EF5CE44B27C832757DFB375B0A72" xlink:to="loc_us-gaap_RangeMember_32DF7702E72443774A457DFB375B824C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_ACC6175C4D59529583117DFB375B8912" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_32DF7702E72443774A457DFB375B824C" xlink:to="loc_us-gaap_MaximumMember_ACC6175C4D59529583117DFB375B8912" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_8027031AC8B5F80A59797DFB375B2C01" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_32DF7702E72443774A457DFB375B824C" xlink:to="loc_us-gaap_MinimumMember_8027031AC8B5F80A59797DFB375B2C01" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_8CB7E7AAFA8F444C32FB7DFB375B07F9" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:to="loc_us-gaap_StatementScenarioAxis_8CB7E7AAFA8F444C32FB7DFB375B07F9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_47491FE480FBBAA0CF027DFB375C6EC4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_8CB7E7AAFA8F444C32FB7DFB375B07F9" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_47491FE480FBBAA0CF027DFB375C6EC4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_47491FE480FBBAA0CF027DFB375C6EC4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_8CB7E7AAFA8F444C32FB7DFB375B07F9" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_47491FE480FBBAA0CF027DFB375C6EC4" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ScenarioOneMember" xlink:label="loc_mrcy_ScenarioOneMember_5032A9E7A8EF0878FA697DFB375CE120" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_47491FE480FBBAA0CF027DFB375C6EC4" xlink:to="loc_mrcy_ScenarioOneMember_5032A9E7A8EF0878FA697DFB375CE120" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ScenarioTwoMember" xlink:label="loc_mrcy_ScenarioTwoMember_D05F8E4A04B1C18CD1837DFB375C02E4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_47491FE480FBBAA0CF027DFB375C6EC4" xlink:to="loc_mrcy_ScenarioTwoMember_D05F8E4A04B1C18CD1837DFB375C02E4" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PeriodTypeAxis" xlink:label="loc_mrcy_PeriodTypeAxis_7C541261537C6C7F3F187DFB375C45F7" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_04709CE952ED22ECC4A97DFB375A7CD5" xlink:to="loc_mrcy_PeriodTypeAxis_7C541261537C6C7F3F187DFB375C45F7" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PeriodTypeDomain" xlink:label="loc_mrcy_PeriodTypeDomain_85F380AD0C166D77A8F07DFB375CECE2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_mrcy_PeriodTypeAxis_7C541261537C6C7F3F187DFB375C45F7" xlink:to="loc_mrcy_PeriodTypeDomain_85F380AD0C166D77A8F07DFB375CECE2_default" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PeriodTypeDomain" xlink:label="loc_mrcy_PeriodTypeDomain_85F380AD0C166D77A8F07DFB375CECE2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_mrcy_PeriodTypeAxis_7C541261537C6C7F3F187DFB375C45F7" xlink:to="loc_mrcy_PeriodTypeDomain_85F380AD0C166D77A8F07DFB375CECE2" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PeriodOneMember" xlink:label="loc_mrcy_PeriodOneMember_0464E69CABC7CBEC529D7DFB375C5F54" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_PeriodTypeDomain_85F380AD0C166D77A8F07DFB375CECE2" xlink:to="loc_mrcy_PeriodOneMember_0464E69CABC7CBEC529D7DFB375C5F54" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_640AF1A33E35866FBD3D7DFB375C2C93" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_640AF1A33E35866FBD3D7DFB375C2C93" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_DebtInstrumentBorrowingPeriod" xlink:label="loc_mrcy_DebtInstrumentBorrowingPeriod_DE40F0D1752F9A9D2A447DFB375CFC1E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_DebtInstrumentBorrowingPeriod_DE40F0D1752F9A9D2A447DFB375CFC1E" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_NumberOfTermLoanBorrowings" xlink:label="loc_mrcy_NumberOfTermLoanBorrowings_A1741D8DC5E3265F5EF47E8A5EC0564C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_NumberOfTermLoanBorrowings_A1741D8DC5E3265F5EF47E8A5EC0564C" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_LineOfCreditFacilityPermitsAdditionalBorrowingsAccordionFeature" xlink:label="loc_mrcy_LineOfCreditFacilityPermitsAdditionalBorrowingsAccordionFeature_C3B9828A2A25D2F3D87F7DFB375C110B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_LineOfCreditFacilityPermitsAdditionalBorrowingsAccordionFeature_C3B9828A2A25D2F3D87F7DFB375C110B" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_LeverageRatio" xlink:label="loc_mrcy_LeverageRatio_A3B2939EFEE5DA609B237DFB375CBBBC" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_LeverageRatio_A3B2939EFEE5DA609B237DFB375CBBBC" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_InterestCoverageRatio" xlink:label="loc_mrcy_InterestCoverageRatio_E7446BECA19A8C337ACA7DFB375C8BE2" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_InterestCoverageRatio_E7446BECA19A8C337ACA7DFB375C8BE2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_0D4B73D3C6F1C9EC5E6D7DFB375CB5BF" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_0D4B73D3C6F1C9EC5E6D7DFB375CB5BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityAmountOutstanding" xlink:label="loc_us-gaap_LineOfCreditFacilityAmountOutstanding_2319447F623BDB9AFE957DFB375C3D40" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_us-gaap_LineOfCreditFacilityAmountOutstanding_2319447F623BDB9AFE957DFB375C3D40" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_FAF7C7308097793B7BCF7DFB375CA429" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_FAF7C7308097793B7BCF7DFB375CA429" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PercentageOfVotingStock" xlink:label="loc_mrcy_PercentageOfVotingStock_22E2BD8E3B47E4B31E617DFB375D0DE9" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_PercentageOfVotingStock_22E2BD8E3B47E4B31E617DFB375D0DE9" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_QuickRatio" xlink:label="loc_mrcy_QuickRatio_61A50793FDD0B4FA3DD47DFB375DF8F2" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_QuickRatio_61A50793FDD0B4FA3DD47DFB375DF8F2" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CashEquivalentsInExcessOfBorrowings" xlink:label="loc_mrcy_CashEquivalentsInExcessOfBorrowings_A9255ABA0B390D345CD67DFB375D269A" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_CashEquivalentsInExcessOfBorrowings_A9255ABA0B390D345CD67DFB375D269A" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CashFlowCovenant" xlink:label="loc_mrcy_CashFlowCovenant_38F1DED1B8326CA6414D7DFB375D95A0" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_56EBE1EC1D35591E58AC7DFB375CACA6" xlink:to="loc_mrcy_CashFlowCovenant_38F1DED1B8326CA6414D7DFB375D95A0" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/DescriptionOfBusiness" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/DescriptionOfBusinessDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/EmployeeBenefitPlans" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/EmployeeBenefitPlansAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57FA9C99CC237FE9C76A7EEB6782864C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_AE48711B2E9677DE90D97EEB6781069D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57FA9C99CC237FE9C76A7EEB6782864C" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_AE48711B2E9677DE90D97EEB6781069D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_1F9A31650A76327CC9477EEB67818380" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_AE48711B2E9677DE90D97EEB6781069D" xlink:to="loc_us-gaap_RangeAxis_1F9A31650A76327CC9477EEB67818380" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_C6F16FA85E3646533C867EEB6781DE45_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_1F9A31650A76327CC9477EEB67818380" xlink:to="loc_us-gaap_RangeMember_C6F16FA85E3646533C867EEB6781DE45_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_C6F16FA85E3646533C867EEB6781DE45" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_1F9A31650A76327CC9477EEB67818380" xlink:to="loc_us-gaap_RangeMember_C6F16FA85E3646533C867EEB6781DE45" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_01195216AFFBCF9ECA7C7EEB67814E96" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_C6F16FA85E3646533C867EEB6781DE45" xlink:to="loc_us-gaap_MaximumMember_01195216AFFBCF9ECA7C7EEB67814E96" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_B196A12E22974948D7C87EEB67826E93" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57FA9C99CC237FE9C76A7EEB6782864C" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_B196A12E22974948D7C87EEB67826E93" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_E23D84B1D00CDACBF6EF7EEB6EF04C49" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_57FA9C99CC237FE9C76A7EEB6782864C" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_E23D84B1D00CDACBF6EF7EEB6EF04C49" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/EstimatedFutureAmortizationExpenseForAcquiredIntangibleAssetsDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/ExpensesByBusinessSegmentForRestructuringPlansDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems" xlink:label="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComponentOfOtherOperatingCostAndExpenseTable" xlink:label="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseTable_89A7B8743A5F0F48161F74DD3B240507" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:to="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseTable_89A7B8743A5F0F48161F74DD3B240507" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_E1988701D6EBB99A023974DD3B24A6D4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseTable_89A7B8743A5F0F48161F74DD3B240507" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_E1988701D6EBB99A023974DD3B24A6D4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_7E2058D4615C06F949F774DD3B2431CD_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_E1988701D6EBB99A023974DD3B24A6D4" xlink:to="loc_us-gaap_SegmentDomain_7E2058D4615C06F949F774DD3B2431CD_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_7E2058D4615C06F949F774DD3B2431CD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_E1988701D6EBB99A023974DD3B24A6D4" xlink:to="loc_us-gaap_SegmentDomain_7E2058D4615C06F949F774DD3B2431CD" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryCommercialElectronicsMember" xlink:label="loc_mrcy_MercuryCommercialElectronicsMember_37053812EF3FCE36129074DD3B24477F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7E2058D4615C06F949F774DD3B2431CD" xlink:to="loc_mrcy_MercuryCommercialElectronicsMember_37053812EF3FCE36129074DD3B24477F" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryDefenseAndIntelligenceSystemsMember" xlink:label="loc_mrcy_MercuryDefenseAndIntelligenceSystemsMember_3B329DC24BB5F7E4EE4674DD3B24B5EF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7E2058D4615C06F949F774DD3B2431CD" xlink:to="loc_mrcy_MercuryDefenseAndIntelligenceSystemsMember_3B329DC24BB5F7E4EE4674DD3B24B5EF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_FC2EC20B7CA45035B09274DD3B2479F5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseTable_89A7B8743A5F0F48161F74DD3B240507" xlink:to="loc_us-gaap_StatementScenarioAxis_FC2EC20B7CA45035B09274DD3B2479F5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_98E56962E232A2FC64BB74DD3B24F861_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_FC2EC20B7CA45035B09274DD3B2479F5" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_98E56962E232A2FC64BB74DD3B24F861_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_98E56962E232A2FC64BB74DD3B24F861" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_FC2EC20B7CA45035B09274DD3B2479F5" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_98E56962E232A2FC64BB74DD3B24F861" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SeveranceMember" xlink:label="loc_mrcy_SeveranceMember_D0E0F8C641ED95572A2974DD3B240E85" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_98E56962E232A2FC64BB74DD3B24F861" xlink:to="loc_mrcy_SeveranceMember_D0E0F8C641ED95572A2974DD3B240E85" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_OtherMembersMember" xlink:label="loc_mrcy_OtherMembersMember_703C059C980B8295DE7F74DD3B24629D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_98E56962E232A2FC64BB74DD3B24F861" xlink:to="loc_mrcy_OtherMembersMember_703C059C980B8295DE7F74DD3B24629D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringReserveCurrent" xlink:label="loc_us-gaap_RestructuringReserveCurrent_774C9B80051B0CBA9A8574DD3B24EAE0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:to="loc_us-gaap_RestructuringReserveCurrent_774C9B80051B0CBA9A8574DD3B24EAE0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_29A4DF54E4CF2B23B93D74DD3B253AE9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:to="loc_us-gaap_RestructuringCharges_29A4DF54E4CF2B23B93D74DD3B253AE9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:label="loc_us-gaap_PaymentsForRestructuring_6BB8A3E2C8903AA9903D74DD3B252549" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:to="loc_us-gaap_PaymentsForRestructuring_6BB8A3E2C8903AA9903D74DD3B252549" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringReserveSettledWithoutCash" xlink:label="loc_us-gaap_RestructuringReserveSettledWithoutCash_C26916BCFBC877B3B43374DD3B256B00" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:to="loc_us-gaap_RestructuringReserveSettledWithoutCash_C26916BCFBC877B3B43374DD3B256B00" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringReserveAccrualAdjustment" xlink:label="loc_us-gaap_RestructuringReserveAccrualAdjustment_36E7498385841D1AB59074DD3B251728" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOperatingOtherCostAndExpenseLineItems_6FB26ACAEC93C5AA450F74DD3B24704E" xlink:to="loc_us-gaap_RestructuringReserveAccrualAdjustment_36E7498385841D1AB59074DD3B251728" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/FairValueOfAcquiredAssetsDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_B8144DF34605ED74C9FC7E386A9651C9" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6228E15848D9E80E516C7E386A917666" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_B8144DF34605ED74C9FC7E386A9651C9" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6228E15848D9E80E516C7E386A917666" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_65C56444B6CAABE067187E386A91C15C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6228E15848D9E80E516C7E386A917666" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_65C56444B6CAABE067187E386A91C15C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_376BFA82E9D2762116AB7E386A914917_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_65C56444B6CAABE067187E386A91C15C" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_376BFA82E9D2762116AB7E386A914917_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_376BFA82E9D2762116AB7E386A914917" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_65C56444B6CAABE067187E386A91C15C" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_376BFA82E9D2762116AB7E386A914917" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_596BA5D44FF6A66A65BC7E386A91DCE2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_376BFA82E9D2762116AB7E386A914917" xlink:to="loc_mrcy_MicroneticsMember_596BA5D44FF6A66A65BC7E386A91DCE2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_461FA416F7F7A846980A7E386A918136" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6228E15848D9E80E516C7E386A917666" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_461FA416F7F7A846980A7E386A918136" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3E9632BBC3CDFAB562757E386A96D036_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_461FA416F7F7A846980A7E386A918136" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3E9632BBC3CDFAB562757E386A96D036_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3E9632BBC3CDFAB562757E386A96D036" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_461FA416F7F7A846980A7E386A918136" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3E9632BBC3CDFAB562757E386A96D036" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_A8929B6167E14E4C8E077E386A96512E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3E9632BBC3CDFAB562757E386A96D036" xlink:to="loc_us-gaap_CustomerRelationshipsMember_A8929B6167E14E4C8E077E386A96512E" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BacklogMember" xlink:label="loc_mrcy_BacklogMember_774C3ACC964E0B1979227E386A96F473" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3E9632BBC3CDFAB562757E386A96D036" xlink:to="loc_mrcy_BacklogMember_774C3ACC964E0B1979227E386A96F473" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_20C6C90DD035BAB67F587E386A96367D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_B8144DF34605ED74C9FC7E386A9651C9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_20C6C90DD035BAB67F587E386A96367D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_97D1411D8943639A48997E386A96E772" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_B8144DF34605ED74C9FC7E386A9651C9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_97D1411D8943639A48997E386A96E772" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_F3AAFBB6D5BE5AA3D0837E386A963AA4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_B8144DF34605ED74C9FC7E386A9651C9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_F3AAFBB6D5BE5AA3D0837E386A963AA4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9C4A8837C202A7BE1A477E386A965F8A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_B8144DF34605ED74C9FC7E386A9651C9" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9C4A8837C202A7BE1A477E386A965F8A" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/FairValueOfFinancialInstruments" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/FairValueOfFinancialInstrumentsAdditionalInformationDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/FairValueOfFinancialInstrumentsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/Goodwill" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/GoodwillAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_508BC0306E2B5687DB5D7E4E42AC918A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_508BC0306E2B5687DB5D7E4E42AC918A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_57645226326B378DC31F7E4E42AC519E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_508BC0306E2B5687DB5D7E4E42AC918A" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_57645226326B378DC31F7E4E42AC519E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_57645226326B378DC31F7E4E42AC519E" xlink:to="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_57645226326B378DC31F7E4E42AC519E" xlink:to="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryDefenseSystemsMember" xlink:label="loc_mrcy_MercuryDefenseSystemsMember_4F41C3CE0341136589F07E4E42AC9C20" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6" xlink:to="loc_mrcy_MercuryDefenseSystemsMember_4F41C3CE0341136589F07E4E42AC9C20" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryIntelligenceSystemsMember" xlink:label="loc_mrcy_MercuryIntelligenceSystemsMember_A8FF649CEBEB0F00B3ED7E4E42AC54A4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6" xlink:to="loc_mrcy_MercuryIntelligenceSystemsMember_A8FF649CEBEB0F00B3ED7E4E42AC54A4" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryCommercialElectronicsMember" xlink:label="loc_mrcy_MercuryCommercialElectronicsMember_12B27386C788E70865017E4E42AC7E7C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1354B2512BD6B5E2A1AF7E4E42AC2BE6" xlink:to="loc_mrcy_MercuryCommercialElectronicsMember_12B27386C788E70865017E4E42AC7E7C" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BusinessCombinationGoodwillImpairmentNumberofMarketAnalyses" xlink:label="loc_mrcy_BusinessCombinationGoodwillImpairmentNumberofMarketAnalyses_35FACB123FEB69BF22337E4E42AC1142" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:to="loc_mrcy_BusinessCombinationGoodwillImpairmentNumberofMarketAnalyses_35FACB123FEB69BF22337E4E42AC1142" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_11547BC1C4C0ECEAE1667E4E42AC6B17" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_11547BC1C4C0ECEAE1667E4E42AC6B17" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_GoodwillImpairmentTestFairValueAssumptionsIncreaseDecreaseInDiscountRate" xlink:label="loc_mrcy_GoodwillImpairmentTestFairValueAssumptionsIncreaseDecreaseInDiscountRate_1C52DE422FA9DB28F39E7E4E42ACA0E9" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:to="loc_mrcy_GoodwillImpairmentTestFairValueAssumptionsIncreaseDecreaseInDiscountRate_1C52DE422FA9DB28F39E7E4E42ACA0E9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_EE7E2F0F399DC21F0A137E4E42AC526F" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:to="loc_us-gaap_NumberOfReportableSegments_EE7E2F0F399DC21F0A137E4E42AC526F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NumberOfOperatingSegments" xlink:label="loc_us-gaap_NumberOfOperatingSegments_2638E292A13137EA9C897E4E42AD3B3D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_55AFFB1B5F70CFD3F4C07E4E42ACDEF1" xlink:to="loc_us-gaap_NumberOfOperatingSegments_2638E292A13137EA9C897E4E42AD3B3D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/GoodwillChangesInCarryingAmountOfGoodwillDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_D5652F3727BB6FFC86D082FDA369F8F0" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_433463281F97B8DAC6B882FDA3688708" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_D5652F3727BB6FFC86D082FDA369F8F0" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_433463281F97B8DAC6B882FDA3688708" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_C8C177DC8082C04AE95B82FDA368DE66" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_433463281F97B8DAC6B882FDA3688708" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_C8C177DC8082C04AE95B82FDA368DE66" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7FC4CE390B8602E2F52E82FDA368377F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_C8C177DC8082C04AE95B82FDA368DE66" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7FC4CE390B8602E2F52E82FDA368377F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7FC4CE390B8602E2F52E82FDA368377F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_C8C177DC8082C04AE95B82FDA368DE66" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7FC4CE390B8602E2F52E82FDA368377F" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_1B1DEC56871FC5FBA1EE82FDA36937D6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7FC4CE390B8602E2F52E82FDA368377F" xlink:to="loc_mrcy_MicroneticsMember_1B1DEC56871FC5FBA1EE82FDA36937D6" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_KORElectronicsMember" xlink:label="loc_mrcy_KORElectronicsMember_BF538B73A5571695523082FDA3692A31" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7FC4CE390B8602E2F52E82FDA368377F" xlink:to="loc_mrcy_KORElectronicsMember_BF538B73A5571695523082FDA3692A31" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_F83383E9E42809CABA3582FDA369CF03" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_433463281F97B8DAC6B882FDA3688708" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_F83383E9E42809CABA3582FDA369CF03" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F83383E9E42809CABA3582FDA369CF03" xlink:to="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F83383E9E42809CABA3582FDA369CF03" xlink:to="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AdvancedComputingSolutionsMember" xlink:label="loc_mrcy_AdvancedComputingSolutionsMember_7E241DD63727F918561582FDA369820A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:to="loc_mrcy_AdvancedComputingSolutionsMember_7E241DD63727F918561582FDA369820A" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryFederalSystemsMember" xlink:label="loc_mrcy_MercuryFederalSystemsMember_2FB42EF8730445ADFC0382FDA369CE81" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:to="loc_mrcy_MercuryFederalSystemsMember_2FB42EF8730445ADFC0382FDA369CE81" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryCommercialElectronicsMember" xlink:label="loc_mrcy_MercuryCommercialElectronicsMember_DB2177CE64E37061C57282FDA3698DD9" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:to="loc_mrcy_MercuryCommercialElectronicsMember_DB2177CE64E37061C57282FDA3698DD9" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryDefenseSystemsMember" xlink:label="loc_mrcy_MercuryDefenseSystemsMember_9414ECD84AEB5FD2035882FDA3696CA0" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:to="loc_mrcy_MercuryDefenseSystemsMember_9414ECD84AEB5FD2035882FDA3696CA0" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryIntelligenceSystemsMember" xlink:label="loc_mrcy_MercuryIntelligenceSystemsMember_689EBFB78F7D11A2347A82FDA369746F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_58FB26EC35F29612A7FF82FDA3690489" xlink:to="loc_mrcy_MercuryIntelligenceSystemsMember_689EBFB78F7D11A2347A82FDA369746F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_D5652F3727BB6FFC86D082FDA369F8F0" xlink:to="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_58C9F444AE02AA293F4E82FDA369AA51" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:to="loc_us-gaap_Goodwill_58C9F444AE02AA293F4E82FDA369AA51" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_CCB473432C9212D13CED82FDA369A23D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_CCB473432C9212D13CED82FDA369A23D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillSubsequentRecognitionOfDeferredTaxAsset" xlink:label="loc_us-gaap_GoodwillSubsequentRecognitionOfDeferredTaxAsset_4121BCBAAC96C62BF84782FDA369500A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:to="loc_us-gaap_GoodwillSubsequentRecognitionOfDeferredTaxAsset_4121BCBAAC96C62BF84782FDA369500A" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_GoodwillSubsequentRecognitionofDeferredTaxLiability" xlink:label="loc_mrcy_GoodwillSubsequentRecognitionofDeferredTaxLiability_2505077CE3C012655EE882FDA36AAC32" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:to="loc_mrcy_GoodwillSubsequentRecognitionofDeferredTaxLiability_2505077CE3C012655EE882FDA36AAC32" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GoodwillAllocationAdjustment" xlink:label="loc_us-gaap_GoodwillAllocationAdjustment_9BCAD1C1D61E4486F87882FDA36AD7AD" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86168504CADCAA04B22682FDA3695028" xlink:to="loc_us-gaap_GoodwillAllocationAdjustment_9BCAD1C1D61E4486F87882FDA36AD7AD" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/GoodwillTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/IncomeTaxes" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/IncomeTaxesAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TaxCreditCarryforwardLineItems" xlink:label="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TaxCreditCarryforwardTable" xlink:label="loc_us-gaap_TaxCreditCarryforwardTable_02408AC699B1474E96D07D855E030456" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:to="loc_us-gaap_TaxCreditCarryforwardTable_02408AC699B1474E96D07D855E030456" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_E313CF6E402B584F14447D855E04EBDA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_02408AC699B1474E96D07D855E030456" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_E313CF6E402B584F14447D855E04EBDA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_3879E72EA0256FA639D57D855E043012_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_E313CF6E402B584F14447D855E04EBDA" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_3879E72EA0256FA639D57D855E043012_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_3879E72EA0256FA639D57D855E043012" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_E313CF6E402B584F14447D855E04EBDA" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_3879E72EA0256FA639D57D855E043012" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_F465D6A0BE28F75AD1F17D855E0599D4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_3879E72EA0256FA639D57D855E043012" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_F465D6A0BE28F75AD1F17D855E0599D4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_FDB68999292DDFEC9E137D855E058DEE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_3879E72EA0256FA639D57D855E043012" xlink:to="loc_us-gaap_ForeignCountryMember_FDB68999292DDFEC9E137D855E058DEE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TaxCreditCarryforwardAxis" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_63BBCD95BD80EA17363E7D855E061308" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_02408AC699B1474E96D07D855E030456" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_63BBCD95BD80EA17363E7D855E061308" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_BFFB76A84FC9977FB9B87D855E064BB8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_63BBCD95BD80EA17363E7D855E061308" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_BFFB76A84FC9977FB9B87D855E064BB8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_BFFB76A84FC9977FB9B87D855E064BB8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_63BBCD95BD80EA17363E7D855E061308" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_BFFB76A84FC9977FB9B87D855E064BB8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ResearchMember" xlink:label="loc_us-gaap_ResearchMember_8FD3ECCCEA8E6AFD66AA7D855E063F8A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_BFFB76A84FC9977FB9B87D855E064BB8" xlink:to="loc_us-gaap_ResearchMember_8FD3ECCCEA8E6AFD66AA7D855E063F8A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InvestmentCreditMember" xlink:label="loc_us-gaap_InvestmentCreditMember_53162B7AA0C43DC684167D855E064B8A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_BFFB76A84FC9977FB9B87D855E064BB8" xlink:to="loc_us-gaap_InvestmentCreditMember_53162B7AA0C43DC684167D855E064B8A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_3787C553F279F02D45E97D855E064E55" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_02408AC699B1474E96D07D855E030456" xlink:to="loc_us-gaap_RangeAxis_3787C553F279F02D45E97D855E064E55" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_9D9AF6AC92EB70508A677D855E0613C9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_3787C553F279F02D45E97D855E064E55" xlink:to="loc_us-gaap_RangeMember_9D9AF6AC92EB70508A677D855E0613C9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_9D9AF6AC92EB70508A677D855E0613C9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_3787C553F279F02D45E97D855E064E55" xlink:to="loc_us-gaap_RangeMember_9D9AF6AC92EB70508A677D855E0613C9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_A7A367A44AFED694958B7D855E0630BF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_9D9AF6AC92EB70508A677D855E0613C9" xlink:to="loc_us-gaap_MinimumMember_A7A367A44AFED694958B7D855E0630BF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_61EFA9EC72ECDB9A4E307D855E072525" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_9D9AF6AC92EB70508A677D855E0613C9" xlink:to="loc_us-gaap_MaximumMember_61EFA9EC72ECDB9A4E307D855E072525" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_2EC45623DA3593C641187D855E07F50A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_2EC45623DA3593C641187D855E07F50A" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_TaxCreditCarryforwardExpirationYear" xlink:label="loc_mrcy_TaxCreditCarryforwardExpirationYear_7D77C3BFE58BDA087CE97D855E07D84D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:to="loc_mrcy_TaxCreditCarryforwardExpirationYear_7D77C3BFE58BDA087CE97D855E07D84D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards_64004CFE71367E28F8F97D855E075D0F" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:to="loc_us-gaap_OperatingLossCarryforwards_64004CFE71367E28F8F97D855E075D0F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_C5FC179D54AD4A1795107D855E07B5C0" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_C5FC179D54AD4A1795107D855E07B5C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_1EF8B7CF856EE92D08477D855E071137" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_A653F1EA766161E728E57D855E073F4B" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_1EF8B7CF856EE92D08477D855E071137" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/IncomeTaxesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/Inventory" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/InventoryAdditionalInformationDetails" xlink:type="extended">
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ScheduleOfInventoryLineItems" xlink:label="loc_mrcy_ScheduleOfInventoryLineItems_8E0BC4469E766B651ECF79ED88D0C439" xlink:type="locator" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ScheduleOfInventoryTable" xlink:label="loc_mrcy_ScheduleOfInventoryTable_CA31A76A204691BAE75D79ED88CFF4BD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_mrcy_ScheduleOfInventoryLineItems_8E0BC4469E766B651ECF79ED88D0C439" xlink:to="loc_mrcy_ScheduleOfInventoryTable_CA31A76A204691BAE75D79ED88CFF4BD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_53A255DA9241EADBCEB079ED88CFB845" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_ScheduleOfInventoryTable_CA31A76A204691BAE75D79ED88CFF4BD" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_53A255DA9241EADBCEB079ED88CFB845" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFE0F1C9E37750E360D479ED88D06F85_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_53A255DA9241EADBCEB079ED88CFB845" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFE0F1C9E37750E360D479ED88D06F85_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFE0F1C9E37750E360D479ED88D06F85" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_53A255DA9241EADBCEB079ED88CFB845" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFE0F1C9E37750E360D479ED88D06F85" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_F9C5229F05FFF29D898779ED88D0B258" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFE0F1C9E37750E360D479ED88D06F85" xlink:to="loc_mrcy_MicroneticsMember_F9C5229F05FFF29D898779ED88D0B258" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_E5EA918C5C04F4BE65E079ED88D0317A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ScheduleOfInventoryLineItems_8E0BC4469E766B651ECF79ED88D0C439" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_E5EA918C5C04F4BE65E079ED88D0317A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InventoryForLongTermContractsOrPrograms" xlink:label="loc_us-gaap_InventoryForLongTermContractsOrPrograms_6DF27F617C16D19641C179ED88D0D624" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ScheduleOfInventoryLineItems_8E0BC4469E766B651ECF79ED88D0C439" xlink:to="loc_us-gaap_InventoryForLongTermContractsOrPrograms_6DF27F617C16D19641C179ED88D0D624" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/InventoryDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/InventoryTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/MinimumLeasePaymentsUnderNonCancelableOperatingLeasesDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomers" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_99E59EF30C9C9ADDFDA9791C4B356A33" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_265F86F15FC170D2BA5E791C4B34D74B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_99E59EF30C9C9ADDFDA9791C4B356A33" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_265F86F15FC170D2BA5E791C4B34D74B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_819EB5AA65F92F7230CF791C4B34C1FC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_265F86F15FC170D2BA5E791C4B34D74B" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_819EB5AA65F92F7230CF791C4B34C1FC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_C2E6B6AB9BB9B627C22A791C4B350994_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_819EB5AA65F92F7230CF791C4B34C1FC" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_C2E6B6AB9BB9B627C22A791C4B350994_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_C2E6B6AB9BB9B627C22A791C4B350994" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_819EB5AA65F92F7230CF791C4B34C1FC" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_C2E6B6AB9BB9B627C22A791C4B350994" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ProgramOneMember" xlink:label="loc_mrcy_ProgramOneMember_18A327B29503591ABE0D791C4B35683D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_C2E6B6AB9BB9B627C22A791C4B350994" xlink:to="loc_mrcy_ProgramOneMember_18A327B29503591ABE0D791C4B35683D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_C3C2E75CF56868E203D1791C4B359441" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_99E59EF30C9C9ADDFDA9791C4B356A33" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_C3C2E75CF56868E203D1791C4B359441" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_EntityWideRevenueMajorProgramNumber" xlink:label="loc_mrcy_EntityWideRevenueMajorProgramNumber_1639A99673B438AF0FE3791C4B35DB05" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_99E59EF30C9C9ADDFDA9791C4B356A33" xlink:to="loc_mrcy_EntityWideRevenueMajorProgramNumber_1639A99673B438AF0FE3791C4B35DB05" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersCustomersComprisingTenPercentOrMoreRevenuesDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_BA5E774DFD77E4F7237A74D49BB35636" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_6DE109FD1B5D8F35852F74D49BB2AA92" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_BA5E774DFD77E4F7237A74D49BB35636" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_6DE109FD1B5D8F35852F74D49BB2AA92" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_A39E2883E9E168B58FAC74D49BB2C6DB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_6DE109FD1B5D8F35852F74D49BB2AA92" xlink:to="loc_us-gaap_MajorCustomersAxis_A39E2883E9E168B58FAC74D49BB2C6DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorCustomersAxis_A39E2883E9E168B58FAC74D49BB2C6DB" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorCustomersAxis_A39E2883E9E168B58FAC74D49BB2C6DB" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CustomerThreeMember" xlink:label="loc_mrcy_CustomerThreeMember_D4D14B6265B34534C8BB74D49BB33B1E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071" xlink:to="loc_mrcy_CustomerThreeMember_D4D14B6265B34534C8BB74D49BB33B1E" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CustomerOneMember" xlink:label="loc_mrcy_CustomerOneMember_39F131C073E55CD8F57E74D49BB3C5D3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071" xlink:to="loc_mrcy_CustomerOneMember_39F131C073E55CD8F57E74D49BB3C5D3" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CustomerTwoMember" xlink:label="loc_mrcy_CustomerTwoMember_BE100D01695BEB43981374D49BB33D58" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_658EAC1D91157593DC6574D49BB31071" xlink:to="loc_mrcy_CustomerTwoMember_BE100D01695BEB43981374D49BB33D58" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerPercentage" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerPercentage_C7098C6AF00548091AF574D49BB35713" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_BA5E774DFD77E4F7237A74D49BB35636" xlink:to="loc_us-gaap_EntityWideRevenueMajorCustomerPercentage_C7098C6AF00548091AF574D49BB35713" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersGeographicDistributionOfRevenuesAndLongLivedAssetsFromContinuingOperationsDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_C4EFD3CD0E1AB7411C6A79019E5A92EB" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_E38B3CA4916205E9CFF979019E54C4C2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_C4EFD3CD0E1AB7411C6A79019E5A92EB" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_E38B3CA4916205E9CFF979019E54C4C2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_18BA568F9BC46A30747579019E546809" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_E38B3CA4916205E9CFF979019E54C4C2" xlink:to="loc_us-gaap_StatementGeographicalAxis_18BA568F9BC46A30747579019E546809" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_18BA568F9BC46A30747579019E546809" xlink:to="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_18BA568F9BC46A30747579019E546809" xlink:to="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2012/country-2012-01-31.xsd#country_US" xlink:label="loc_country_US_60FC1E92D512522D185F79019E5959B0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22" xlink:to="loc_country_US_60FC1E92D512522D185F79019E5959B0" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_EuropeMember" xlink:label="loc_mrcy_EuropeMember_9B517A598673F9D2E3FF79019E59ACE3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22" xlink:to="loc_mrcy_EuropeMember_9B517A598673F9D2E3FF79019E59ACE3" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AsiaPacificMember" xlink:label="loc_mrcy_AsiaPacificMember_873A020C338F60D78B2279019E5AB9C8" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22" xlink:to="loc_mrcy_AsiaPacificMember_873A020C338F60D78B2279019E5AB9C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GeographicalIntersegmentEliminationsMember" xlink:label="loc_us-gaap_GeographicalIntersegmentEliminationsMember_8E46CF1C759781D1FE4079019E5A0928" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_AFC5F4A863325480896679019E549B22" xlink:to="loc_us-gaap_GeographicalIntersegmentEliminationsMember_8E46CF1C759781D1FE4079019E5A0928" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToIndividualForeignCountries" xlink:label="loc_mrcy_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToIndividualForeignCountries_D8004BD1D112BF096B6C79019E5A0F42" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_C4EFD3CD0E1AB7411C6A79019E5A92EB" xlink:to="loc_mrcy_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToIndividualForeignCountries_D8004BD1D112BF096B6C79019E5A0F42" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_RevenuesFromTransactionsWithOtherGeographicLocationsOfSameEntity" xlink:label="loc_mrcy_RevenuesFromTransactionsWithOtherGeographicLocationsOfSameEntity_756776A9C29484B5A4D479019E5A7768" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_C4EFD3CD0E1AB7411C6A79019E5A92EB" xlink:to="loc_mrcy_RevenuesFromTransactionsWithOtherGeographicLocationsOfSameEntity_756776A9C29484B5A4D479019E5A7768" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_C30F0DAA44EE3AA853CD79019E5A5FE1" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_C4EFD3CD0E1AB7411C6A79019E5A92EB" xlink:to="loc_us-gaap_Revenues_C30F0DAA44EE3AA853CD79019E5A5FE1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EntityWideDisclosureOnGeographicAreasLongLivedAssetsInEntitysCountryOfDomicile" xlink:label="loc_us-gaap_EntityWideDisclosureOnGeographicAreasLongLivedAssetsInEntitysCountryOfDomicile_00575402C13B54DC720379019E5A67A3" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_C4EFD3CD0E1AB7411C6A79019E5A92EB" xlink:to="loc_us-gaap_EntityWideDisclosureOnGeographicAreasLongLivedAssetsInEntitysCountryOfDomicile_00575402C13B54DC720379019E5A67A3" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersReconcilesNetIncomeMostDirectlyComparableGaapFinancialMeasureToAdjustedEbitdaDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersSummaryOfPerformanceOfOperationsByReportableSegmentDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_172FF4DC58ADA6D5530B79019E8890ED" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_FF084FA32A3822B3870879019E88241E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_172FF4DC58ADA6D5530B79019E8890ED" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_FF084FA32A3822B3870879019E88241E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_139AA9BE9A3D5DD15D1979019E88E3D4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_FF084FA32A3822B3870879019E88241E" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_139AA9BE9A3D5DD15D1979019E88E3D4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_139AA9BE9A3D5DD15D1979019E88E3D4" xlink:to="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_139AA9BE9A3D5DD15D1979019E88E3D4" xlink:to="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryCommercialElectronicsMember" xlink:label="loc_mrcy_MercuryCommercialElectronicsMember_ECA6BDB9D68EC17F64C379019E8883E9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0" xlink:to="loc_mrcy_MercuryCommercialElectronicsMember_ECA6BDB9D68EC17F64C379019E8883E9" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryDefenseAndIntelligenceSystemsMember" xlink:label="loc_mrcy_MercuryDefenseAndIntelligenceSystemsMember_3A8D9C7C20532ABB272079019E8846A0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0" xlink:to="loc_mrcy_MercuryDefenseAndIntelligenceSystemsMember_3A8D9C7C20532ABB272079019E8846A0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_03B116E6ADE159DC97B179019E8859C7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2B8901F130FD9AF8B1E079019E8831F0" xlink:to="loc_us-gaap_IntersegmentEliminationMember_03B116E6ADE159DC97B179019E8859C7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RevenuesFromExternalCustomers" xlink:label="loc_us-gaap_RevenuesFromExternalCustomers_7F5706CBF04B184CCA4579019E8994A4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_172FF4DC58ADA6D5530B79019E8890ED" xlink:to="loc_us-gaap_RevenuesFromExternalCustomers_7F5706CBF04B184CCA4579019E8994A4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity" xlink:label="loc_us-gaap_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity_0AEBE726A049C7044FB179019E897DF6" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_172FF4DC58ADA6D5530B79019E8890ED" xlink:to="loc_us-gaap_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity_0AEBE726A049C7044FB179019E897DF6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_4817CF7059921F28DFC079019E893523" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_172FF4DC58ADA6D5530B79019E8890ED" xlink:to="loc_us-gaap_Revenues_4817CF7059921F28DFC079019E893523" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization" xlink:label="loc_mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization_146E733CD2F029F50F4E79019E8ED891" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_172FF4DC58ADA6D5530B79019E8890ED" xlink:to="loc_mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization_146E733CD2F029F50F4E79019E8ED891" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/OperatingSegmentGeographicInformationAndSignificantCustomersTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/PropertyAndEquipment" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/PropertyAndEquipmentAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D99D313D9186E40E9F3F82FDA3738316" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D99D313D9186E40E9F3F82FDA3738316" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_C563061DFB996C3C760882FDA3734CCF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D99D313D9186E40E9F3F82FDA3738316" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_C563061DFB996C3C760882FDA3734CCF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_DCBF2B49F20B6FFF6A3E82FDA373F8ED_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_C563061DFB996C3C760882FDA3734CCF" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_DCBF2B49F20B6FFF6A3E82FDA373F8ED_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_DCBF2B49F20B6FFF6A3E82FDA373F8ED" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_C563061DFB996C3C760882FDA3734CCF" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_DCBF2B49F20B6FFF6A3E82FDA373F8ED" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_RestructuringandOtherChargesMember" xlink:label="loc_mrcy_RestructuringandOtherChargesMember_B897950338882763C62682FDA3735E83" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_DCBF2B49F20B6FFF6A3E82FDA373F8ED" xlink:to="loc_mrcy_RestructuringandOtherChargesMember_B897950338882763C62682FDA3735E83" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F6AC67DE26C66D44120582FDA373F4EE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D99D313D9186E40E9F3F82FDA3738316" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F6AC67DE26C66D44120582FDA373F4EE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B914C1086E3DC6326A9F82FDA373D3F7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F6AC67DE26C66D44120582FDA373F4EE" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B914C1086E3DC6326A9F82FDA373D3F7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B914C1086E3DC6326A9F82FDA373D3F7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F6AC67DE26C66D44120582FDA373F4EE" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B914C1086E3DC6326A9F82FDA373D3F7" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ComputersEquipmentAndSoftwareMember" xlink:label="loc_mrcy_ComputersEquipmentAndSoftwareMember_493F341C7FA4377CB48382FDA373390B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_B914C1086E3DC6326A9F82FDA373D3F7" xlink:to="loc_mrcy_ComputersEquipmentAndSoftwareMember_493F341C7FA4377CB48382FDA373390B" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_AssetsDisposed" xlink:label="loc_mrcy_AssetsDisposed_94C1718FFB135145C77082FDA3734697" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_mrcy_AssetsDisposed_94C1718FFB135145C77082FDA3734697" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_8A6ECD75571B9EB8234F82FDA3742089" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_us-gaap_Depreciation_8A6ECD75571B9EB8234F82FDA3742089" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_B09534C3FB34CE1352E882FDA3749C32" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_B09534C3FB34CE1352E882FDA3749C32" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SaleLeasebackTransactionDeferredGainGross" xlink:label="loc_us-gaap_SaleLeasebackTransactionDeferredGainGross_BB30F8EB68D605BC1FE582FDA3741E57" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_us-gaap_SaleLeasebackTransactionDeferredGainGross_BB30F8EB68D605BC1FE582FDA3741E57" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SaleLeasebackTransactionLeaseTerm" xlink:label="loc_mrcy_SaleLeasebackTransactionLeaseTerm_EA36DF2B9C9534FD8D4F82FDA3740E5C" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_mrcy_SaleLeasebackTransactionLeaseTerm_EA36DF2B9C9534FD8D4F82FDA3740E5C" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_SaleLeasebackTransactionLeaseTermsNumberOfRenewalOption" xlink:label="loc_mrcy_SaleLeasebackTransactionLeaseTermsNumberOfRenewalOption_CC5F3413C0B074E4EDA582FDA37416F2" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_mrcy_SaleLeasebackTransactionLeaseTermsNumberOfRenewalOption_CC5F3413C0B074E4EDA582FDA37416F2" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_LeaseTermOptiontoRenew" xlink:label="loc_mrcy_LeaseTermOptiontoRenew_7BE549FF9571CF07DCEA82FDA3748645" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3984E580839555AD987182FDA3730310" xlink:to="loc_mrcy_LeaseTermOptiontoRenew_7BE549FF9571CF07DCEA82FDA3748645" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/PropertyAndEquipmentDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_44DCAB9AECCD5D86633D79714E50D2BC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_44DCAB9AECCD5D86633D79714E50D2BC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_466F55E08ED276AA57BB79714E50B130" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_44DCAB9AECCD5D86633D79714E50D2BC" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_466F55E08ED276AA57BB79714E50B130" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_466F55E08ED276AA57BB79714E50B130" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_466F55E08ED276AA57BB79714E50B130" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ComputersEquipmentAndSoftwareMember" xlink:label="loc_mrcy_ComputersEquipmentAndSoftwareMember_2A9D8D532CE14B7C5E8079714E506694" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:to="loc_mrcy_ComputersEquipmentAndSoftwareMember_2A9D8D532CE14B7C5E8079714E506694" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_BC54212019F56BC2E9F979714E512352" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_BC54212019F56BC2E9F979714E512352" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_BuildingAndLeaseholdImprovementsMember" xlink:label="loc_mrcy_BuildingAndLeaseholdImprovementsMember_17705B418E31AE5C48D479714E515533" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:to="loc_mrcy_BuildingAndLeaseholdImprovementsMember_17705B418E31AE5C48D479714E515533" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_3E04708A17868CD48C0C79714E5166F3" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_3E04708A17868CD48C0C79714E5166F3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_VehiclesMember" xlink:label="loc_us-gaap_VehiclesMember_77EAE9534238A6FAB7C279714E51A969" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_79F85590942120F4172779714E508BA3" xlink:to="loc_us-gaap_VehiclesMember_77EAE9534238A6FAB7C279714E51A969" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_B6DD0EBBF806964C82C879714E516F85" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_44DCAB9AECCD5D86633D79714E50D2BC" xlink:to="loc_us-gaap_RangeAxis_B6DD0EBBF806964C82C879714E516F85" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_0D5EB5F9FC8114E4650D79714E51E37D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_B6DD0EBBF806964C82C879714E516F85" xlink:to="loc_us-gaap_RangeMember_0D5EB5F9FC8114E4650D79714E51E37D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_0D5EB5F9FC8114E4650D79714E51E37D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_B6DD0EBBF806964C82C879714E516F85" xlink:to="loc_us-gaap_RangeMember_0D5EB5F9FC8114E4650D79714E51E37D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_51B1EC41EE7925A4733679714E514729" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_0D5EB5F9FC8114E4650D79714E51E37D" xlink:to="loc_us-gaap_MinimumMember_51B1EC41EE7925A4733679714E514729" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_C00FAF4DB27C0383037179714E516B9D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_0D5EB5F9FC8114E4650D79714E51E37D" xlink:to="loc_us-gaap_MaximumMember_C00FAF4DB27C0383037179714E516B9D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ADD4391683B13C1428E879714E5250CD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ADD4391683B13C1428E879714E5250CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives_76B5679768BC67AF774A79714E523340" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives_76B5679768BC67AF774A79714E523340" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_14200C2B9A8A66D15C7F79714E52CC5E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_14200C2B9A8A66D15C7F79714E52CC5E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_C05F71955A7F7A72C80379714E52F0E2" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_C05F71955A7F7A72C80379714E52F0E2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_9D432508A0140D37A24979714E52F2B2" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_B5F6644BA38BEA9CF5C379714E517051" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_9D432508A0140D37A24979714E52F2B2" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/PropertyAndEquipmentTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/ReconciliationBetweenStatutoryFederalIncomeTaxRateAndEffectiveIncomeTaxRateFromContinuingOperationsDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/RestructuringPlan" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/RestructuringPlanAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_3EF3C6C942F01FF9D96574DD3B28AA20" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_78DBFD20E0BE04B2D73F74DD3B2895FF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_3EF3C6C942F01FF9D96574DD3B28AA20" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_78DBFD20E0BE04B2D73F74DD3B2895FF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_AE44BBC31FB1F14F6DA574DD3B28297F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_78DBFD20E0BE04B2D73F74DD3B2895FF" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_AE44BBC31FB1F14F6DA574DD3B28297F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_F84C906330D5FA59249474DD3B28DB8A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AE44BBC31FB1F14F6DA574DD3B28297F" xlink:to="loc_us-gaap_SegmentDomain_F84C906330D5FA59249474DD3B28DB8A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_F84C906330D5FA59249474DD3B28DB8A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AE44BBC31FB1F14F6DA574DD3B28297F" xlink:to="loc_us-gaap_SegmentDomain_F84C906330D5FA59249474DD3B28DB8A" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MercuryCommercialElectronicsMember" xlink:label="loc_mrcy_MercuryCommercialElectronicsMember_B0CF38E5F3A119BCE06474DD3B28D7FF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_F84C906330D5FA59249474DD3B28DB8A" xlink:to="loc_mrcy_MercuryCommercialElectronicsMember_B0CF38E5F3A119BCE06474DD3B28D7FF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_D3995F31BDF3B5BFA11B74DD3B28C372" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_3EF3C6C942F01FF9D96574DD3B28AA20" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_D3995F31BDF3B5BFA11B74DD3B28C372" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_BBE20B31A6B17205548674DD3B28CF16" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_3EF3C6C942F01FF9D96574DD3B28AA20" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_BBE20B31A6B17205548674DD3B28CF16" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_7604780FAF3AE508153674DD3B2895FB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_3EF3C6C942F01FF9D96574DD3B28AA20" xlink:to="loc_us-gaap_RestructuringCharges_7604780FAF3AE508153674DD3B2895FB" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/RestructuringPlanTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/RollForwardOfFairValueOfContingentConsiderationDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/ShareholdersEquity" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/ShareholdersEquityAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ShareholdersEquityLineItems" xlink:label="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:type="locator" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ShareholdersEquityTable" xlink:label="loc_mrcy_ShareholdersEquityTable_14BAB98E8B56CDB0655E766BC3633E1E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_mrcy_ShareholdersEquityTable_14BAB98E8B56CDB0655E766BC3633E1E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareholdersEquityClassAxis" xlink:label="loc_us-gaap_ShareholdersEquityClassAxis_E7FBF4B12A6CFC312BFF766BC36328BE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_ShareholdersEquityTable_14BAB98E8B56CDB0655E766BC3633E1E" xlink:to="loc_us-gaap_ShareholdersEquityClassAxis_E7FBF4B12A6CFC312BFF766BC36328BE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByShareholdersEquityClassDomain" xlink:label="loc_us-gaap_FairValueByShareholdersEquityClassDomain_2545A31CDD73F9781630766BC3631DB1_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareholdersEquityClassAxis_E7FBF4B12A6CFC312BFF766BC36328BE" xlink:to="loc_us-gaap_FairValueByShareholdersEquityClassDomain_2545A31CDD73F9781630766BC3631DB1_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByShareholdersEquityClassDomain" xlink:label="loc_us-gaap_FairValueByShareholdersEquityClassDomain_2545A31CDD73F9781630766BC3631DB1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareholdersEquityClassAxis_E7FBF4B12A6CFC312BFF766BC36328BE" xlink:to="loc_us-gaap_FairValueByShareholdersEquityClassDomain_2545A31CDD73F9781630766BC3631DB1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_821A6545D4ED64113D19766BC363EF60" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueByShareholdersEquityClassDomain_2545A31CDD73F9781630766BC3631DB1" xlink:to="loc_us-gaap_CommonStockMember_821A6545D4ED64113D19766BC363EF60" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComponentOfOtherOperatingCostAndExpenseGeneralAxis" xlink:label="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseGeneralAxis_6ED7E0D1DC14D2A41D4F766BC3634145" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_ShareholdersEquityTable_14BAB98E8B56CDB0655E766BC3633E1E" xlink:to="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseGeneralAxis_6ED7E0D1DC14D2A41D4F766BC3634145" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain" xlink:label="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain_2EDED1BB02183B387FE2766BC363D504_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseGeneralAxis_6ED7E0D1DC14D2A41D4F766BC3634145" xlink:to="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain_2EDED1BB02183B387FE2766BC363D504_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain" xlink:label="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain_2EDED1BB02183B387FE2766BC363D504" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseGeneralAxis_6ED7E0D1DC14D2A41D4F766BC3634145" xlink:to="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain_2EDED1BB02183B387FE2766BC363D504" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_UnderwritingDiscountMember" xlink:label="loc_mrcy_UnderwritingDiscountMember_DD28DD043A0DC87CEB5F766BC364D664" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain_2EDED1BB02183B387FE2766BC363D504" xlink:to="loc_mrcy_UnderwritingDiscountMember_DD28DD043A0DC87CEB5F766BC364D664" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherExpenseMember" xlink:label="loc_us-gaap_OtherExpenseMember_603A1DAF4E80844BFD6D766BC3647225" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentOfOtherOperatingCostAndExpenseNameDomain_2EDED1BB02183B387FE2766BC363D504" xlink:to="loc_us-gaap_OtherExpenseMember_603A1DAF4E80844BFD6D766BC3647225" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_A4ACDADA68D8936D8367766BC364133D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_A4ACDADA68D8936D8367766BC364133D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityIssuancePerShareAmount" xlink:label="loc_us-gaap_EquityIssuancePerShareAmount_2E0DC9AB5016744FFE79766BC36436C3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_EquityIssuancePerShareAmount_2E0DC9AB5016744FFE79766BC36436C3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_EDC72C7B9E0E0C020AAA766BC36437FC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_EDC72C7B9E0E0C020AAA766BC36437FC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts_BF8243B0FBB53436A5BF766BC3643EE4" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts_BF8243B0FBB53436A5BF766BC3643EE4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_52A5EA3005EC16060F50766BC3644000" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_52A5EA3005EC16060F50766BC3644000" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_2834085152FA77B0883F766BC36433FB" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_2834085152FA77B0883F766BC36433FB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" xlink:label="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_3DDA2456E4DADCD83749766BC3649E6B" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_3DDA2456E4DADCD83749766BC3649E6B" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MinimumPercentageOfOutstandingStockAcquiredForRightsToBeExercisable" xlink:label="loc_mrcy_MinimumPercentageOfOutstandingStockAcquiredForRightsToBeExercisable_8BF2A7A6F1814DACC0BE766BC364B233" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareholdersEquityLineItems_9FC588B8EEA776D1B438766BC364719C" xlink:to="loc_mrcy_MinimumPercentageOfOutstandingStockAcquiredForRightsToBeExercisable_8BF2A7A6F1814DACC0BE766BC364B233" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensation" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensationAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C246AB9F2F5BB856D50D78AB16CB4153" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C246AB9F2F5BB856D50D78AB16CB4153" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_CE64D652976D1BF4BFD178AB16CB31C9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C246AB9F2F5BB856D50D78AB16CB4153" xlink:to="loc_us-gaap_AwardTypeAxis_CE64D652976D1BF4BFD178AB16CB31C9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_CE64D652976D1BF4BFD178AB16CB31C9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_CE64D652976D1BF4BFD178AB16CB31C9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_05239EEA6C90482DE62278AB16CBD216" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127" xlink:to="loc_us-gaap_RestrictedStockMember_05239EEA6C90482DE62278AB16CBD216" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_38DF7E438558BFCD967778AB16CBA776" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127" xlink:to="loc_us-gaap_EmployeeStockMember_38DF7E438558BFCD967778AB16CBA776" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockOptionsMember" xlink:label="loc_us-gaap_StockOptionsMember_5B016E40699FFA7E5FCC78AB7BEABAE0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5546EBB8037106EB4AED78AB16CB1127" xlink:to="loc_us-gaap_StockOptionsMember_5B016E40699FFA7E5FCC78AB7BEABAE0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_9D82A5EFF5322F8CC13178AB16CBF8CD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C246AB9F2F5BB856D50D78AB16CB4153" xlink:to="loc_us-gaap_PlanNameAxis_9D82A5EFF5322F8CC13178AB16CBF8CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_F769131318230536E58A78AB16CC6802_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_9D82A5EFF5322F8CC13178AB16CBF8CD" xlink:to="loc_us-gaap_PlanNameDomain_F769131318230536E58A78AB16CC6802_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_F769131318230536E58A78AB16CC6802" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_9D82A5EFF5322F8CC13178AB16CBF8CD" xlink:to="loc_us-gaap_PlanNameDomain_F769131318230536E58A78AB16CC6802" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_StockOptionPlanTwentyZeroFiveMember" xlink:label="loc_mrcy_StockOptionPlanTwentyZeroFiveMember_243EDD78934DC451543F78AB16CCDDFF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_F769131318230536E58A78AB16CC6802" xlink:to="loc_mrcy_StockOptionPlanTwentyZeroFiveMember_243EDD78934DC451543F78AB16CCDDFF" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_StockOptionPlanNineteenNinetySevenMember" xlink:label="loc_mrcy_StockOptionPlanNineteenNinetySevenMember_E2463CB532D9B20227A378AB16D10557" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_F769131318230536E58A78AB16CC6802" xlink:to="loc_mrcy_StockOptionPlanNineteenNinetySevenMember_E2463CB532D9B20227A378AB16D10557" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_B9243A075CA2028626A978AB16D14012" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C246AB9F2F5BB856D50D78AB16CB4153" xlink:to="loc_us-gaap_RangeAxis_B9243A075CA2028626A978AB16D14012" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_B9243A075CA2028626A978AB16D14012" xlink:to="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_B9243A075CA2028626A978AB16D14012" xlink:to="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockOptionsMember" xlink:label="loc_us-gaap_StockOptionsMember_54BBED40C7954E0FE78F78AB16D1A73E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27" xlink:to="loc_us-gaap_StockOptionsMember_54BBED40C7954E0FE78F78AB16D1A73E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_DFEF3AC75F8610D54B6478AB16D1275E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27" xlink:to="loc_us-gaap_MaximumMember_DFEF3AC75F8610D54B6478AB16D1275E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_3DC77DC9844330B18F8178AB16D17CEB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_73F2ABBD577EDD2A1C2078AB16D19D27" xlink:to="loc_us-gaap_MinimumMember_3DC77DC9844330B18F8178AB16D17CEB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_71414147A7483927351D78AB16D1E0FE" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C246AB9F2F5BB856D50D78AB16CB4153" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_71414147A7483927351D78AB16D1E0FE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFC5760BBBC4EF9B9CFE78AB16D14593_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_71414147A7483927351D78AB16D1E0FE" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFC5760BBBC4EF9B9CFE78AB16D14593_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFC5760BBBC4EF9B9CFE78AB16D14593" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_71414147A7483927351D78AB16D1E0FE" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFC5760BBBC4EF9B9CFE78AB16D14593" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_KORElectronicsMember" xlink:label="loc_mrcy_KORElectronicsMember_E2A15C71932212F34A2C78AB16D12DEE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFC5760BBBC4EF9B9CFE78AB16D14593" xlink:to="loc_mrcy_KORElectronicsMember_E2A15C71932212F34A2C78AB16D12DEE" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_06F8AF367EE783902EA978AB16D25664" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FFC5760BBBC4EF9B9CFE78AB16D14593" xlink:to="loc_mrcy_MicroneticsMember_06F8AF367EE783902EA978AB16D25664" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_8BFFEFBB34F07CBF8DB778AB16D2CE92" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_8BFFEFBB34F07CBF8DB778AB16D2CE92" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_0713BFE7A710D93DC3ED78AB16D23874" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_0713BFE7A710D93DC3ED78AB16D23874" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MinimumGrantDateFairValueOfNonqualifiedStockOptionsAsPercentageOfFairValueOfCommonStock" xlink:label="loc_mrcy_MinimumGrantDateFairValueOfNonqualifiedStockOptionsAsPercentageOfFairValueOfCommonStock_10A9024543E1BBC8830A78AB16D2FC5E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_mrcy_MinimumGrantDateFairValueOfNonqualifiedStockOptionsAsPercentageOfFairValueOfCommonStock_10A9024543E1BBC8830A78AB16D2FC5E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_D729B9442A309A69997778AB16D2C280" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_D729B9442A309A69997778AB16D2C280" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardContractualLife" xlink:label="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardContractualLife_F0950DD6C14A593AC3E078AB16D2F18F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardContractualLife_F0950DD6C14A593AC3E078AB16D2F18F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_8E8B0B23CBEA6BCB7CBB78AB16D27BB6" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_8E8B0B23CBEA6BCB7CBB78AB16D27BB6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate_8E3A6A18283D4FF210E578AB16D2ED54" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate_8E3A6A18283D4FF210E578AB16D2ED54" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_EmployeeStockPurchasePlanMaximumPercentageOfCompensationToPurchaseSharesByEligibleParticipants" xlink:label="loc_mrcy_EmployeeStockPurchasePlanMaximumPercentageOfCompensationToPurchaseSharesByEligibleParticipants_87395C107280FB9E3BD578AB16D2CB83" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_mrcy_EmployeeStockPurchasePlanMaximumPercentageOfCompensationToPurchaseSharesByEligibleParticipants_87395C107280FB9E3BD578AB16D2CB83" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_F128E35148BE4826EBA278AB16D2D700" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_F128E35148BE4826EBA278AB16D2D700" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_70DEC0A707401475F0FC78AB16D29F2F" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_70DEC0A707401475F0FC78AB16D29F2F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_7B65D74593969BA09AB478AB16D23273" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_7B65D74593969BA09AB478AB16D23273" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_BB6B2AB0293E77620A2878AB16D28AA8" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_BB6B2AB0293E77620A2878AB16D28AA8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_64D91CCA9E28855B0A0B78AB16D20D88" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_64D91CCA9E28855B0A0B78AB16D20D88" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_9CF716AC945DB456E41F78AB16D29055" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_9CF716AC945DB456E41F78AB16D29055" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_8486DB0A65D1F53B171078AB16D2C870" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2FBDDAA0AE36363AB49778AB16D21A7A" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_8486DB0A65D1F53B171078AB16D2C870" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensationStockBasedCompensationExpensesDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_249D122D01083DDF9E487802F8B0E806" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F643AA1E73A079EF6C067802F8B0291C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_249D122D01083DDF9E487802F8B0E806" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F643AA1E73A079EF6C067802F8B0291C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis_FB1F3017DBF0C53ABFF57802F8B0C6AE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F643AA1E73A079EF6C067802F8B0291C" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis_FB1F3017DBF0C53ABFF57802F8B0C6AE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis_FB1F3017DBF0C53ABFF57802F8B0C6AE" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis_FB1F3017DBF0C53ABFF57802F8B0C6AE" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_7910346B5AF7C7FC7C5B7802F8B03EC8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D" xlink:to="loc_us-gaap_CostOfSalesMember_7910346B5AF7C7FC7C5B7802F8B03EC8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_CEA61A9ED633C2462D617802F8B062B3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_CEA61A9ED633C2462D617802F8B062B3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_F94D5AA166FCEC0E8BE77802F8B0032E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsReportLineDomain_6B08C7E535B647C5A6B37802F8B0F19D" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_F94D5AA166FCEC0E8BE77802F8B0032E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_3A59270FEB926269DF607802F8B1E389" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_249D122D01083DDF9E487802F8B0E806" xlink:to="loc_us-gaap_ShareBasedCompensation_3A59270FEB926269DF607802F8B1E389" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_93B0566917BB85E5DFB97802F8B11EDA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_249D122D01083DDF9E487802F8B0E806" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_93B0566917BB85E5DFB97802F8B11EDA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_83CEBFD8AD4ED6F90A8B7802F8B19387" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_249D122D01083DDF9E487802F8B0E806" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_83CEBFD8AD4ED6F90A8B7802F8B19387" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensationSummaryOfNonvestedRestrictedStockDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A6C5549B5C54499AFD4B7578B63DB9D7" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_33F95B4A9963BDC532637578B63DBE33" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A6C5549B5C54499AFD4B7578B63DB9D7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_33F95B4A9963BDC532637578B63DBE33" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_C34BC6FD2E7E7694BC9D7578B63DA695" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_33F95B4A9963BDC532637578B63DBE33" xlink:to="loc_us-gaap_AwardTypeAxis_C34BC6FD2E7E7694BC9D7578B63DA695" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_953B0EF9784F86BF4AE37578B63DC981_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_C34BC6FD2E7E7694BC9D7578B63DA695" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_953B0EF9784F86BF4AE37578B63DC981_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_953B0EF9784F86BF4AE37578B63DC981" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_C34BC6FD2E7E7694BC9D7578B63DA695" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_953B0EF9784F86BF4AE37578B63DC981" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_8066C31B82C2891504E17578B63D55DE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_953B0EF9784F86BF4AE37578B63DC981" xlink:to="loc_us-gaap_RestrictedStockMember_8066C31B82C2891504E17578B63D55DE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7785E250A6D99C529D7E7578B63DAC7D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A6C5549B5C54499AFD4B7578B63DB9D7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7785E250A6D99C529D7E7578B63DAC7D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_9C43A7467CB67192481A7578B63D919F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7785E250A6D99C529D7E7578B63DAC7D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_9C43A7467CB67192481A7578B63D919F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_506548B21CD2AFF858657578B63D61F0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7785E250A6D99C529D7E7578B63DAC7D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_506548B21CD2AFF858657578B63D61F0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_9C366134C8AC4917F5127578B63D6C05" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7785E250A6D99C529D7E7578B63DAC7D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_9C366134C8AC4917F5127578B63D6C05" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_C14BDF30FDDE19E2837D7578B63D6647" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_7785E250A6D99C529D7E7578B63DAC7D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_C14BDF30FDDE19E2837D7578B63D6647" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_F2227D41EF46008B70E57578B63D2582" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A6C5549B5C54499AFD4B7578B63DB9D7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_F2227D41EF46008B70E57578B63D2582" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_65A1728E7CDC7AB72B837578B63DC2D9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_F2227D41EF46008B70E57578B63D2582" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_65A1728E7CDC7AB72B837578B63DC2D9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_DA1487CC8D9B51F46B5D7578B63DDD1C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_F2227D41EF46008B70E57578B63D2582" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_DA1487CC8D9B51F46B5D7578B63DDD1C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_A04C41C7A0257F0503AD7578B63E2359" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_F2227D41EF46008B70E57578B63D2582" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_A04C41C7A0257F0503AD7578B63E2359" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_FE713E7A9CB282875E457578B63E3449" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_F2227D41EF46008B70E57578B63D2582" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_FE713E7A9CB282875E457578B63E3449" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensationSummaryOfStockOptionPlansDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BC68D32282ADEEF3FF6979C34AB03974" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BC68D32282ADEEF3FF6979C34AB03974" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_52763200CC4C7565009E79C34AB00EBF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BC68D32282ADEEF3FF6979C34AB03974" xlink:to="loc_us-gaap_AwardTypeAxis_52763200CC4C7565009E79C34AB00EBF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_231B8F65E2BD3D69FC6279C34AB054EA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_52763200CC4C7565009E79C34AB00EBF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_231B8F65E2BD3D69FC6279C34AB054EA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_231B8F65E2BD3D69FC6279C34AB054EA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_52763200CC4C7565009E79C34AB00EBF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_231B8F65E2BD3D69FC6279C34AB054EA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockOptionsMember" xlink:label="loc_us-gaap_StockOptionsMember_CD40101F2D6CD974DB9B79C34AB1D830" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_231B8F65E2BD3D69FC6279C34AB054EA" xlink:to="loc_us-gaap_StockOptionsMember_CD40101F2D6CD974DB9B79C34AB1D830" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_28B4717E2C2DFF2B6A9279C34AB15D7E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_28B4717E2C2DFF2B6A9279C34AB15D7E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_CB6336082FE8E97E498579C34AB1123E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_28B4717E2C2DFF2B6A9279C34AB15D7E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_CB6336082FE8E97E498579C34AB1123E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_5160D3A6268474DEE94A79C34AB158B7" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_28B4717E2C2DFF2B6A9279C34AB15D7E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_5160D3A6268474DEE94A79C34AB158B7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_561145E4DD2C526D015979C34AB1A4D9" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_28B4717E2C2DFF2B6A9279C34AB15D7E" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_561145E4DD2C526D015979C34AB1A4D9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_3EBD1CCA511559CC4FD179C34AB15805" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_28B4717E2C2DFF2B6A9279C34AB15D7E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_3EBD1CCA511559CC4FD179C34AB15805" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_B1A299B74654BC08D87579C34AB125E0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_B1A299B74654BC08D87579C34AB125E0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_A83ACBD3A9E639F629D679C34AB1DAF2" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_A83ACBD3A9E639F629D679C34AB1DAF2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_385F8861FABB6C179F8979C34AB2EE2D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_385F8861FABB6C179F8979C34AB2EE2D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_E0BA260D909C51E2602079C34AB269EC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_385F8861FABB6C179F8979C34AB2EE2D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_E0BA260D909C51E2602079C34AB269EC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_5B6818A821E6C8E621DA79C34AB2F6DF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_385F8861FABB6C179F8979C34AB2EE2D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_5B6818A821E6C8E621DA79C34AB2F6DF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_A4F7384698E3295B829479C34AB21209" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_385F8861FABB6C179F8979C34AB2EE2D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_A4F7384698E3295B829479C34AB21209" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_C9A8C2C8593D348A4CF779C34AB27B3E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_385F8861FABB6C179F8979C34AB2EE2D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_C9A8C2C8593D348A4CF779C34AB27B3E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_004AB8BB1A7D4AEAECAB79C34AB2A97C" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_004AB8BB1A7D4AEAECAB79C34AB2A97C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_E73F8326231522F91C5B79C34AB35F8D" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_E73F8326231522F91C5B79C34AB35F8D" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" xlink:label="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_EE217B8BCD639C8EF27979C34AB3C7D1" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_EE217B8BCD639C8EF27979C34AB3C7D1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_E72259FFD8F01A602ED179C34AB3A72D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_EE217B8BCD639C8EF27979C34AB3C7D1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_E72259FFD8F01A602ED179C34AB3A72D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_9946E1600FED034EE82179C34AB3C637" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_EE217B8BCD639C8EF27979C34AB3C7D1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_9946E1600FED034EE82179C34AB3C637" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_AA8C340F3D6188CDFBF779C34AB3A912" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_EE217B8BCD639C8EF27979C34AB3C7D1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_AA8C340F3D6188CDFBF779C34AB3A912" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract" xlink:label="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_72984C263CCBA8C63C3379C34AB39055" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_B86BD47F285B357723CC79C34AB1AF2B" xlink:to="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_72984C263CCBA8C63C3379C34AB39055" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_F54048C39B7B8B13847379C34AB3FA8C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_72984C263CCBA8C63C3379C34AB39055" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_F54048C39B7B8B13847379C34AB3FA8C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_AF39AF89D3B125C6633379C34AB39E5F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_72984C263CCBA8C63C3379C34AB39055" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_AF39AF89D3B125C6633379C34AB39E5F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_855627A8791EDB8DBC9A79C34AB3B9DA" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract_72984C263CCBA8C63C3379C34AB39055" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_855627A8791EDB8DBC9A79C34AB3B9DA" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensationTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/StockBasedCompensationWeighedAverageKeyAssumptionsAndFairValueResultsForStockOptionsGrantedDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SubsequentEvents" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfFinancialAssetsMeasuredAtFairValueOnRecurringBasisDetail" xlink:type="extended">
    <loc xlink:href="mrcy-20130630.xsd#mrcy_FairValueMeasurementsLineItems" xlink:label="loc_mrcy_FairValueMeasurementsLineItems_5472A30F95A3C016E3A1750E1302DFF0" xlink:type="locator" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_FairValueMeasurementsTable" xlink:label="loc_mrcy_FairValueMeasurementsTable_5BAB4A850ECE504380E0750E1301DC4D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_mrcy_FairValueMeasurementsLineItems_5472A30F95A3C016E3A1750E1302DFF0" xlink:to="loc_mrcy_FairValueMeasurementsTable_5BAB4A850ECE504380E0750E1301DC4D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2DFB2E2144F073D3FCAD7510717B6FB7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_FairValueMeasurementsTable_5BAB4A850ECE504380E0750E1301DC4D" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2DFB2E2144F073D3FCAD7510717B6FB7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_B74398B9BB1EFBDCA1257510717DF7DA_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2DFB2E2144F073D3FCAD7510717B6FB7" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_B74398B9BB1EFBDCA1257510717DF7DA_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_B74398B9BB1EFBDCA1257510717DF7DA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2DFB2E2144F073D3FCAD7510717B6FB7" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_B74398B9BB1EFBDCA1257510717DF7DA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_EC4A63E1F6B146544B937510717D8D9B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_B74398B9BB1EFBDCA1257510717DF7DA" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_EC4A63E1F6B146544B937510717D8D9B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_79B40BF498C93E2C2C1B750E130146B5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_FairValueMeasurementsTable_5BAB4A850ECE504380E0750E1301DC4D" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_79B40BF498C93E2C2C1B750E130146B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_79B40BF498C93E2C2C1B750E130146B5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_79B40BF498C93E2C2C1B750E130146B5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_D50293621B8655F7ABCB750E1301964F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_D50293621B8655F7ABCB750E1301964F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_4B06D9098246240A80AB750E1301A670" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_4B06D9098246240A80AB750E1301A670" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_D1A2614D3B861F6A08BE750E1301A1C3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_D1A2614D3B861F6A08BE750E1301A1C3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_213FFAB856D6E8B91039750E13010714" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_79777C2B10EF7C7A79F5750E1301D699" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_213FFAB856D6E8B91039750E13010714" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis_73C8DE2721F6A609D12B750E1301A462" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_FairValueMeasurementsTable_5BAB4A850ECE504380E0750E1301DC4D" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis_73C8DE2721F6A609D12B750E1301A462" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis_73C8DE2721F6A609D12B750E1301A462" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingDisclosureItemAmountsAxis_73C8DE2721F6A609D12B750E1301A462" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_USTreasuryBillSecuritiesMember" xlink:label="loc_us-gaap_USTreasuryBillSecuritiesMember_9EA405E1895C82F46601750E13022226" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5" xlink:to="loc_us-gaap_USTreasuryBillSecuritiesMember_9EA405E1895C82F46601750E13022226" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsMember" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_0402EEE8DFD9967D77FD750E13025457" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_0402EEE8DFD9967D77FD750E13025457" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_RestrictedCashMember" xlink:label="loc_mrcy_RestrictedCashMember_1CB370B28EF64F87EF59750E13024617" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_26D723B4CC12CF8EFB3B750E130191A5" xlink:to="loc_mrcy_RestrictedCashMember_1CB370B28EF64F87EF59750E13024617" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_7D7A6D5AC7AEE702D12D750E1302CCFF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_FairValueMeasurementsLineItems_5472A30F95A3C016E3A1750E1302DFF0" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_7D7A6D5AC7AEE702D12D750E1302CCFF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_C74914005968A6354763750E1302B479" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_7D7A6D5AC7AEE702D12D750E1302CCFF" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_C74914005968A6354763750E1302B479" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfReservesForUnrecognizedIncomeTaxBenefitsDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesBasicAndDilutedWeightedAverageSharesOutstandingDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_5A37799CEA0F8B8173637DA07271416A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable" xlink:label="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_93D5E4C780D7CAC678C57DA07270C03A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_5A37799CEA0F8B8173637DA07271416A" xlink:to="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_93D5E4C780D7CAC678C57DA07270C03A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_466C8D507FDE788F28037DA07270F691" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_93D5E4C780D7CAC678C57DA07270C03A" xlink:to="loc_us-gaap_RangeAxis_466C8D507FDE788F28037DA07270F691" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_E0EEEDB4991B368CA5917DA07270E724_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_466C8D507FDE788F28037DA07270F691" xlink:to="loc_us-gaap_RangeMember_E0EEEDB4991B368CA5917DA07270E724_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_E0EEEDB4991B368CA5917DA07270E724" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_466C8D507FDE788F28037DA07270F691" xlink:to="loc_us-gaap_RangeMember_E0EEEDB4991B368CA5917DA07270E724" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_81032CE109C5D53F5CD57DA07271337C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_E0EEEDB4991B368CA5917DA07270E724" xlink:to="loc_us-gaap_MaximumMember_81032CE109C5D53F5CD57DA07271337C" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CashAndCashEquivalentMaturityPeriod" xlink:label="loc_mrcy_CashAndCashEquivalentMaturityPeriod_3CCC2560A804A4FE62037DA072713535" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_5A37799CEA0F8B8173637DA07271416A" xlink:to="loc_mrcy_CashAndCashEquivalentMaturityPeriod_3CCC2560A804A4FE62037DA072713535" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesChangesInProductWarrantyAccrualDetails" xlink:type="extended">
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ChangesinProductWarrantyAccrualLineItems" xlink:label="loc_mrcy_ChangesinProductWarrantyAccrualLineItems_1F06AB5FA5B492CC65F284422E83A957" xlink:type="locator" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ChangesinProductWarrantyAccrualTable" xlink:label="loc_mrcy_ChangesinProductWarrantyAccrualTable_6C26A3B04F284740E95D84422E829E80" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_mrcy_ChangesinProductWarrantyAccrualLineItems_1F06AB5FA5B492CC65F284422E83A957" xlink:to="loc_mrcy_ChangesinProductWarrantyAccrualTable_6C26A3B04F284740E95D84422E829E80" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_DFC280B821EE3AC1A21D84422E82CE24" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_mrcy_ChangesinProductWarrantyAccrualTable_6C26A3B04F284740E95D84422E829E80" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_DFC280B821EE3AC1A21D84422E82CE24" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26D7D0C3E819AE2F5C5984422E8245B1_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_DFC280B821EE3AC1A21D84422E82CE24" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26D7D0C3E819AE2F5C5984422E8245B1_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26D7D0C3E819AE2F5C5984422E8245B1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_DFC280B821EE3AC1A21D84422E82CE24" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26D7D0C3E819AE2F5C5984422E8245B1" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MicroneticsMember" xlink:label="loc_mrcy_MicroneticsMember_80CA78C7225FEEB94AB384422E8270D4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_26D7D0C3E819AE2F5C5984422E8245B1" xlink:to="loc_mrcy_MicroneticsMember_80CA78C7225FEEB94AB384422E8270D4" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_ProductWarrantyTerm" xlink:label="loc_mrcy_ProductWarrantyTerm_00C4F5684DFA5C6CA4C884422E8889BA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ChangesinProductWarrantyAccrualLineItems_1F06AB5FA5B492CC65F284422E83A957" xlink:to="loc_mrcy_ProductWarrantyTerm_00C4F5684DFA5C6CA4C884422E8889BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward" xlink:label="loc_us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward_301D34B8698071C269BD84422E881CD7" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mrcy_ChangesinProductWarrantyAccrualLineItems_1F06AB5FA5B492CC65F284422E83A957" xlink:to="loc_us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward_301D34B8698071C269BD84422E881CD7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProductWarrantyAccrual" xlink:label="loc_us-gaap_ProductWarrantyAccrual_FDE72C9B2CBA101127D684422E88CB0B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward_301D34B8698071C269BD84422E881CD7" xlink:to="loc_us-gaap_ProductWarrantyAccrual_FDE72C9B2CBA101127D684422E88CB0B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProductWarrantyAccrualAdditionsFromBusinessAcquisition" xlink:label="loc_us-gaap_ProductWarrantyAccrualAdditionsFromBusinessAcquisition_AB8072425BCF38BF364384422E885CEB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward_301D34B8698071C269BD84422E881CD7" xlink:to="loc_us-gaap_ProductWarrantyAccrualAdditionsFromBusinessAcquisition_AB8072425BCF38BF364384422E885CEB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProductWarrantyAccrualWarrantiesIssued" xlink:label="loc_us-gaap_ProductWarrantyAccrualWarrantiesIssued_5D8E224CDA244465DA6684422E88F3E1" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward_301D34B8698071C269BD84422E881CD7" xlink:to="loc_us-gaap_ProductWarrantyAccrualWarrantiesIssued_5D8E224CDA244465DA6684422E88F3E1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProductWarrantyAccrualPayments" xlink:label="loc_us-gaap_ProductWarrantyAccrualPayments_6CD97475522B916C9C5784422E88ECBE" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInStandardAndExtendedProductWarrantyIncreaseDecreaseRollForward_301D34B8698071C269BD84422E881CD7" xlink:to="loc_us-gaap_ProductWarrantyAccrualPayments_6CD97475522B916C9C5784422E88ECBE" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesConcentrationOfRiskDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesIncomeTaxesDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesIntangibleAssetsDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0617C66B21B94CB3734B78D446659A4B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_C1103FAD610C2495194278D40E8C76AC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0617C66B21B94CB3734B78D446659A4B" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_C1103FAD610C2495194278D40E8C76AC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_C0FCE6949095F119A1E478D40E8F9541" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_C1103FAD610C2495194278D40E8C76AC" xlink:to="loc_us-gaap_RangeAxis_C0FCE6949095F119A1E478D40E8F9541" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6EB7E07D63420E9222EB78D40E8FAD34_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_C0FCE6949095F119A1E478D40E8F9541" xlink:to="loc_us-gaap_RangeMember_6EB7E07D63420E9222EB78D40E8FAD34_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6EB7E07D63420E9222EB78D40E8FAD34" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_C0FCE6949095F119A1E478D40E8F9541" xlink:to="loc_us-gaap_RangeMember_6EB7E07D63420E9222EB78D40E8FAD34" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_B278A484C6B10D8AE8A378D40E8F8320" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_6EB7E07D63420E9222EB78D40E8FAD34" xlink:to="loc_us-gaap_MaximumMember_B278A484C6B10D8AE8A378D40E8F8320" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_490E3E370E22C1B51D8E78D4466EE786" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0617C66B21B94CB3734B78D446659A4B" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_490E3E370E22C1B51D8E78D4466EE786" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesNetEarningsPerShareAdditionalInformationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_370DF90DBDF7AB90543978B427A87A55" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_39C8261504102D4A1D3A78B427A86186" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_370DF90DBDF7AB90543978B427A87A55" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_39C8261504102D4A1D3A78B427A86186" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareholdersEquityClassAxis" xlink:label="loc_us-gaap_ShareholdersEquityClassAxis_FED9F3F6E0ECEED5F42F78B427A87EE0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_39C8261504102D4A1D3A78B427A86186" xlink:to="loc_us-gaap_ShareholdersEquityClassAxis_FED9F3F6E0ECEED5F42F78B427A87EE0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByShareholdersEquityClassDomain" xlink:label="loc_us-gaap_FairValueByShareholdersEquityClassDomain_F7CA29BDF68756914C7078B427A8B7A9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareholdersEquityClassAxis_FED9F3F6E0ECEED5F42F78B427A87EE0" xlink:to="loc_us-gaap_FairValueByShareholdersEquityClassDomain_F7CA29BDF68756914C7078B427A8B7A9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByShareholdersEquityClassDomain" xlink:label="loc_us-gaap_FairValueByShareholdersEquityClassDomain_F7CA29BDF68756914C7078B427A8B7A9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareholdersEquityClassAxis_FED9F3F6E0ECEED5F42F78B427A87EE0" xlink:to="loc_us-gaap_FairValueByShareholdersEquityClassDomain_F7CA29BDF68756914C7078B427A8B7A9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_911E72F8FF98913DDCA378B427A88163" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueByShareholdersEquityClassDomain_F7CA29BDF68756914C7078B427A8B7A9" xlink:to="loc_us-gaap_CommonStockMember_911E72F8FF98913DDCA378B427A88163" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_087AC28650608C969A3D78B427A895A6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_370DF90DBDF7AB90543978B427A87A55" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_087AC28650608C969A3D78B427A895A6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityIssuancePerShareAmount" xlink:label="loc_us-gaap_EquityIssuancePerShareAmount_B322B17F1698B066D58578B427A83B8A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_370DF90DBDF7AB90543978B427A87A55" xlink:to="loc_us-gaap_EquityIssuancePerShareAmount_B322B17F1698B066D58578B427A83B8A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_9B34C4AFDB78E83F5E5078B427A929A4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_370DF90DBDF7AB90543978B427A87A55" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_9B34C4AFDB78E83F5E5078B427A929A4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:label="loc_us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_24E28FD9AD83E04D382878B427A96B31" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_370DF90DBDF7AB90543978B427A87A55" xlink:to="loc_us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_24E28FD9AD83E04D382878B427A96B31" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesPrinciplesOfConsolidationDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesReclassificationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_8BC550C880DE2FF73D517DA3C0AA5182" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable" xlink:label="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_1C54640CACFD1E006DC57DA3C0A5FB81" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_8BC550C880DE2FF73D517DA3C0AA5182" xlink:to="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_1C54640CACFD1E006DC57DA3C0A5FB81" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_05B8BC837ED217082AC67DA4AD7BFE22" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_1C54640CACFD1E006DC57DA3C0A5FB81" xlink:to="loc_us-gaap_StatementScenarioAxis_05B8BC837ED217082AC67DA4AD7BFE22" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_BEA87290CC37191FDCDB7DA4AEC0CFDC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_05B8BC837ED217082AC67DA4AD7BFE22" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_BEA87290CC37191FDCDB7DA4AEC0CFDC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_BEA87290CC37191FDCDB7DA4AEC0CFDC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_05B8BC837ED217082AC67DA4AD7BFE22" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_BEA87290CC37191FDCDB7DA4AEC0CFDC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioPreviouslyReportedMember" xlink:label="loc_us-gaap_ScenarioPreviouslyReportedMember_1698DFDCF82CFAF777097DA4D88FAFDE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_BEA87290CC37191FDCDB7DA4AEC0CFDC" xlink:to="loc_us-gaap_ScenarioPreviouslyReportedMember_1698DFDCF82CFAF777097DA4D88FAFDE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestatementAdjustmentMember" xlink:label="loc_us-gaap_RestatementAdjustmentMember_77413326FED8962AA7227DA855CC85AC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_BEA87290CC37191FDCDB7DA4AEC0CFDC" xlink:to="loc_us-gaap_RestatementAdjustmentMember_77413326FED8962AA7227DA855CC85AC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_3054E18028006E5906837DA471DB81F2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_8BC550C880DE2FF73D517DA3C0AA5182" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_3054E18028006E5906837DA471DB81F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_A90F5B5B21C6F08887387DA92993928B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_8BC550C880DE2FF73D517DA3C0AA5182" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_A90F5B5B21C6F08887387DA92993928B" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesRestrictedCashDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_5BB55FE8D1878EDFCF30750E139D238E" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable" xlink:label="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_B0FCFBD2E5196C12D7EB750E139D9C1F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_5BB55FE8D1878EDFCF30750E139D238E" xlink:to="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_B0FCFBD2E5196C12D7EB750E139D9C1F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_60400DFA7CBA927CE799750E139D21DE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestrictedCashAndCashEquivalentsTable_B0FCFBD2E5196C12D7EB750E139D9C1F" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_60400DFA7CBA927CE799750E139D21DE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_E2035374AD0AD4FC8770750E139D85BB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_60400DFA7CBA927CE799750E139D21DE" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_E2035374AD0AD4FC8770750E139D85BB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_E2035374AD0AD4FC8770750E139D85BB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_60400DFA7CBA927CE799750E139D21DE" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_E2035374AD0AD4FC8770750E139D85BB" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_CashCollateralMember" xlink:label="loc_mrcy_CashCollateralMember_DAF4369E767A0B35B314750E139D7DB8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_E2035374AD0AD4FC8770750E139D85BB" xlink:to="loc_mrcy_CashCollateralMember_DAF4369E767A0B35B314750E139D7DB8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_8B6D0C0EED43BEAF6DAB750E139D9C4D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems_5BB55FE8D1878EDFCF30750E139D238E" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_8B6D0C0EED43BEAF6DAB750E139D9C4D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesRevenueRecognitionDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueArrangementLineItems" xlink:label="loc_us-gaap_DeferredRevenueArrangementLineItems_705A8B324AD1341EE77D750E13A243E7" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueArrangementByTypeTable" xlink:label="loc_us-gaap_DeferredRevenueArrangementByTypeTable_3D5B362EDD8F9AFE147F750E13A21D17" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DeferredRevenueArrangementLineItems_705A8B324AD1341EE77D750E13A243E7" xlink:to="loc_us-gaap_DeferredRevenueArrangementByTypeTable_3D5B362EDD8F9AFE147F750E13A21D17" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="loc_us-gaap_DeferredRevenueArrangementTypeAxis_930A52AB2227201133EF750E13A2AE72" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DeferredRevenueArrangementByTypeTable_3D5B362EDD8F9AFE147F750E13A21D17" xlink:to="loc_us-gaap_DeferredRevenueArrangementTypeAxis_930A52AB2227201133EF750E13A2AE72" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="loc_us-gaap_DeferredRevenueArrangementTypeDomain_AE0EC2ECBCE4A1C38746750E13A25875_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeAxis_930A52AB2227201133EF750E13A2AE72" xlink:to="loc_us-gaap_DeferredRevenueArrangementTypeDomain_AE0EC2ECBCE4A1C38746750E13A25875_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="loc_us-gaap_DeferredRevenueArrangementTypeDomain_AE0EC2ECBCE4A1C38746750E13A25875" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeAxis_930A52AB2227201133EF750E13A2AE72" xlink:to="loc_us-gaap_DeferredRevenueArrangementTypeDomain_AE0EC2ECBCE4A1C38746750E13A25875" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_MultipleDeliveryRevenueMember" xlink:label="loc_mrcy_MultipleDeliveryRevenueMember_6D270201E68CC9A2C86A750E13A220E8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeDomain_AE0EC2ECBCE4A1C38746750E13A25875" xlink:to="loc_mrcy_MultipleDeliveryRevenueMember_6D270201E68CC9A2C86A750E13A220E8" xlink:type="arc" />
    <loc xlink:href="mrcy-20130630.xsd#mrcy_PercentageOfRevenueRecognized" xlink:label="loc_mrcy_PercentageOfRevenueRecognized_A08227B038AD8C7CBAF7750E13A22DE3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementLineItems_705A8B324AD1341EE77D750E13A243E7" xlink:to="loc_mrcy_PercentageOfRevenueRecognized_A08227B038AD8C7CBAF7750E13A22DE3" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://mcry.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SupplementaryInformationUnaudited" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SupplementaryInformationUnauditedDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/SupplementaryInformationUnauditedTables" xlink:type="extended" />
  <definitionLink xlink:role="http://mcry.com/role/UnamortizedDeferredGainDetail" xlink:type="extended" />
</linkbase>
