The word is used since the beginning of the 20th century in Mathematics. It has been built from the Latin verb denumerare meaning to count out.
denumerable (not comparable)
- (mathematics) Capable of being assigned numbers from the natural numbers. Especially applied to sets where finite sets and sets that have a one-to-one mapping to the natural numbers are called denumerable.
- The empty set is denumerable because it is finite; the rational numbers are, surprisingly, denumerable because every possible fraction can be assigned a number.