Source : Webster's Revised Unabridged Dictionary (1913)

Countable \Count"a*ble\ (-?-b'l), a.
   Capable of being numbered.

Source : WordNet®

countable
     adj : that can be counted; "countable sins"; "numerable assets"
           [syn: {denumerable}, {enumerable}, {numerable}]

Source : Free On-Line Dictionary of Computing

countable
     
         A term describing a {set} which is {isomorphic}
        to a subet of the {natural numbers}.  A countable set has
        "countably many" elements.  If the isomorphism is stated
        explicitly then the set is called "a counted set" or "an
        {enumeration}".
     
        Examples of countable sets are any {finite} set, the {natural
        numbers}, {integers}, and {rational numbers}.  The {real
        numbers} and {complex numbers} are not [proof?].
     
        (1999-08-29)