Dictionary
ax'iom of countabil'ity
Math.
the property satisfied by a topological space in which the neighborhood system of each point has a base consisting of a countable number of neighborhoods
(first axiom of countability) or the property satisfied by a topological space that has a base for its topology consisting of a countable number of subsets of the space
(second axiom of countability). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.