countably many

from The Free On-line Dictionary of Computing (8 July 2008)

countable
countably many
uncountable

   <mathematics> 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)