<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>5</documentType>

    <periodOfReport>2005-12-31</periodOfReport>

    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000921847</issuerCik>
        <issuerName>HUDSON CITY BANCORP INC</issuerName>
        <issuerTradingSymbol>HCBK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001206752</rptOwnerCik>
            <rptOwnerName>SALAMONE DENIS J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>WEST 80 CENTURY ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PARAMUS</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07652</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Executive VP</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>565662</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3412</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By PIB</value>
                    <footnoteId id="F9"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>249890</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By GRAT</value>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>176330</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6412</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By IRA</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>128240</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Spouse</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01/share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14565</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By ESOP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>12.22</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-02-18</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>320599</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>320599</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.59</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2011-10-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>820736</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>820736</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12622</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F7"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12622</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31713</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On June 7, 2005, the common stock of Hudson City Bancorp, Inc. split 3.206-for-1, resulting in the reporting person's acquisition of 2.206 additional shares of common stock for each share owned as of June 6, 2005 less fractional shares cashed-out. The number of shares and stock options reported have been adjusted to reflect the 3.206-for-1 stock split.</footnote>
        <footnote id="F2">Since the reporting person's previous report, the reporting person transferred 70,710 shares from a grantor retained annuity trust to the reporting person's joint account.</footnote>
        <footnote id="F3">Award to the reporting person of 15,000 shares of common stock pursuant to the Hudson City Bancorp, Inc. 2000 Recognition and Retention Plan (&quot;RRP&quot;), which the stockholders approved at a Special Meeting of Stockholders of Hudson City Bancorp, Inc. held on January 13, 2000 (&quot;Special Meeting&quot;), effective February 19, 2004. The shares awarded were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005. Such award will vest at a rate of 20% per year on each of April 20, 2006, 2007, 2008, 2009 and 2010. Previous award to the reporting person of 100,000 shares of common stock pursuant to the Denis J. Salamone Restricted Stock Award Plan (&quot;the Plan&quot;), was made by the Board of Directors, effective November 9, 2001.  On April 20, 2002, 20,000 shares vested and became directly owned by the reporting person.  (Footnote 3 continues in Footnote 4.)</footnote>
        <footnote id="F4">The shares awarded pursuant to the Plan were adjusted to reflect a 2-for-1 stock split on June 17, 2002 and on each of April 20, 2003, 2004 and 2005 an additional 40,000 shares vested and became directly owned by the reporting person.  The shares awarded were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005 and 128,240 shares will vest on April 20, 2006.  Such shares are subject to legend until vested.</footnote>
        <footnote id="F5">Grant to reporting person of options to buy 100,000 shares of common stock pursuant to the Hudson City Bancorp, Inc. 2000 Stock Option Plan, approved at the Special Meeting, was made by the Board of Directors, effective February 19, 2004. The options awarded and the exercise price of those options were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005 and 64,120 options vested and became exercisable on January 13, 2006.  The remaining options will vest and become exercisable at a rate of 64,120 shares per year on each of January 13, 2007, 2008, 2009 and 2010.    (Footnote 5 continues in Footnote 6.)</footnote>
        <footnote id="F6">Previous grant to the reporting person of options to buy 160,000 shares of common stock pursuant to the Stock Option Agreement for Denis J. Salamone was made by the Board of Directors, effective October 29, 2001.  Options to buy 32,000 shares of common stock vested and became exercisable on January 13, 2002.  The options awarded to the reporting person were adjusted to reflect a 2-for-1 stock split on June 17, 2002 and 64,000 options vested and  became exercisable on each of January 13, 2003, 2004 and 2005.  The options awarded were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005 and 205,184 options vested and became exercisable on January 13, 2006.</footnote>
        <footnote id="F7">The reporting person is due upon retirement the equivalent dollar value of 31,713 shares of HCBK common stock as of December 31, 2005 through the Hudson City Savings Bank ESOP Restoration Plan.</footnote>
        <footnote id="F8">The shares reported are held in a grantor retained annuity trust that was established for the benefit of the reporting person's children.  The reporting person is the grantor and the reporting person and his children serve as trustees.</footnote>
        <footnote id="F9">Shares are held in the reporting person's account in the Hudson City Savings Bank Profit Incentive Bonus Plan at December 31, 2005.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Louis J. Beierle, Attorney-in-fact</signatureName>
        <signatureDate>2006-02-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
