Definition from Wiktionary, the free dictionary
countable (not comparable)
- Capable of being counted; having a quantity.
- (mathematics, of a set) Finite or countably infinite; having a one-to-one correspondence (bijection) with a subset of the natural numbers.
- (mathematics, of a set) Countably infinite; having a bijection with the natural numbers.
- (grammar, of a noun) Freely usable with the indefinite article and with numbers, and therefore having a plural form.
The mathematics sense by which finite sets are countable is more common than the sense by which finite sets are not countable.
- (having a bijection with a subset of the natural numbers): denumerable
- (countably infinite): infinite
capable of being counted, having a quantity
math: having a bijection with a subset of the natural numbers
grammar: freely used with numbers and the definite article