countable set A set that is either finite or countably infinite. A countably infinite set is one that can be put in one-to-one correspondence with the natural numbers and thus has a cardinal number ("size") of aleph-null. Examples of countable sets include the set of all people on Earth and the set of all fractions. Related entry infinity Related category SETS AND SET THEORY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |