<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType><periodOfReport>2004-01-09</periodOfReport>
    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000716133</issuerCik>
        <issuerName>CINCINNATI BELL INC</issuerName>
        <issuerTradingSymbol>CBB</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001276079</rptOwnerCik>
            <rptOwnerName>ROSS BRIAN A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>201 EAST FOURTH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CINCINNATI</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>45202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Chief Finanical Officer</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>9822</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>727</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By 401k Plan</value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>200</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By IRA</value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1758</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Children</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>18.3438</value></conversionOrExercisePrice><exerciseDate><value>2002-01-04</value></exerciseDate><expirationDate><value>2009-09-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>400</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>17.50</value></conversionOrExercisePrice><exerciseDate><value>2002-09-13</value></exerciseDate><expirationDate><value>2009-09-13</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>15000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>35.9688</value></conversionOrExercisePrice><exerciseDate><value>2003-01-03</value></exerciseDate><expirationDate><value>2010-01-03</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>25000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>22.8438</value></conversionOrExercisePrice><exerciseDate><value>2004-01-01</value></exerciseDate><expirationDate><value>2011-01-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>20000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>16.425</value></conversionOrExercisePrice><exerciseDate><value>2001-09-05</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2011-09-05</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>9.645</value></conversionOrExercisePrice><exerciseDate><value>2001-12-04</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2011-12-04</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>25000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>3.48</value></conversionOrExercisePrice><exerciseDate><value>2002-12-05</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2012-12-05</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>60000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy </value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>5.655</value></conversionOrExercisePrice><exerciseDate><value>2003-12-04</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2013-12-04</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>60000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Option to Buy</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>5.655</value></conversionOrExercisePrice><exerciseDate><value>2003-12-04</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2013-12-04</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><footnotes><footnote id="F1">Option shares granted under the Cincinnati Bell Inc. 1997 Long Term Incentive Plan which is a Rule 16b-3 Plan.  </footnote><footnote id="F2">Options have a 3 year vesting schedule: 28% one year from grant date and 3% for each of the remaining 24 months.  </footnote></footnotes><remarks/><ownerSignature><signatureName>Amy Collins, Attorney-in-fact for Brian A. Ross</signatureName><signatureDate>2004-01-14</signatureDate></ownerSignature></ownershipDocument>

