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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-04-20</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001312132</rptOwnerCik>
            <rptOwnerName>Klarer James A</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <transactionDate>
                <value>2006-04-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3768</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.44</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>105293</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F7"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>34625</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>41089</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By PIB</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17545</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By ESOP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>600</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Daughter</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stk Optn(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.16</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2001-01-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2010-01-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>70150</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>70150</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stk Optn(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.20</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-01-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>19236</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19236</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stk Optn(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.17</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-01-21</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>48090</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>48090</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stk Optn(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>12.22</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-02-19</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>64119</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>64119</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Award to the reporting person of 10,000 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;), was effective January 21, 2005. The shares awarded were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005 and 6,412 shares vested and became directly owned by the reporting person on April 20, 2006.  Such award will vest at a rate of 6,412 shares per year on each of April 20, 2007, 2008, 2009 and 2010. Previous award to the reporting person of 3,500 shares of common stock pursuant to the RRP was made by the Board of Directors, effective February 19, 2004. The shares awarded were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005 and 2,244 shares vested and became directly owned by the reporting person on April 20, 2006.  (Footnote 1 continues in Footnote 2)</footnote>
        <footnote id="F2">Such award will vest at a rate of 2,244 shares per year on each of April 20, 2007, 2008, 2009 and 2010. Previous award to the reporting person of 2,900 shares of common stock pursuant to the RRP was made by the Board of Directors, effective Janaury 10, 2002.  On April 20, 2002, 580 shares vested and became directly owned by the reporting person.The shares awarded pursuant to the RRP were adjusted to reflect a 2-for-1 stock split on June 17, 2002 and on each of April 20, 2003, 2004 and 2005, 1,160 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 3,718 shares vested and became directly owned by the reporting person on April 20, 2006.</footnote>
        <footnote id="F3">Shares are held in the reporting person's account in the Hudson City Savings Bank Profit Incentive Bonus Plan at December 31, 2005.</footnote>
        <footnote id="F4">Grant to the reporting person of options to buy 15,000 shares of common stock pursuant to the Hudson City Bancorp, Inc. 2000 Stock Option Plan (&quot;the Plan&quot;) that was approved by stockholders at the Special Meeting was effective Janaury 21, 2005.  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 9,618 options vested and became exercisable on January 13, 2006.  The remaining options will vest at a rate of 20% per year on each of January 13, 2007, 2008, 2009 and 2010. (Footnote 4 continues in Footnote 5)</footnote>
        <footnote id="F5">Previous grant to the reporting person of options to buy 20,000 shares of common stock pursuant to the Plan 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 12,824 options vested and became exercisable on January 13, 2006. The remaining award will vest and become exercisable at a rate of 20% per year on each of January 13, 2007, 2008, 2009 and 2010.  (Footnote 6 continues in Footnote 7)</footnote>
        <footnote id="F6">Previous grant to the reporting person of options to buy 5,000 shares of common stock pursuant to the Plan was made by the Board of Directors, effective January 10, 2002.The 5,000 options awarded to the reporting person were adjusted to reflect a 2-for-1 stock split on June 17, 2002 and 2,000 options vested and  became exercisable on each of January 13, 2003, 2004 and 2005.  The remaining unvested options were adjusted to reflect a 3.206-for-1 stock split on June 7, 2005 and 6,412 options vested and became exercisable on January 13, 2006.  The remaining 6,412 options will vest and become exercisable on January 13, 2007.</footnote>
        <footnote id="F7">The reported transaction represents shares withheld by the issuer to satisfy payroll tax withholding obligations of the reporting person upon vesting of common stock pursuant to Hudson City Bancorp, Inc.'s 2000 RRP.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>James A, Klarer</signatureName>
        <signatureDate>2006-04-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
