Adjective

Wikipedia Wikipedia countable (not comparable)

Positive countable

Comparative not comparable

Superlative none (absolute)

1. Capable of being counted; having a quantity or a numerical attribute.
2. (mathematics, of a set) Having a bijection with a subset of the natural numbers.
3. (mathematics, of a set) Countably infinite; having a bijection with the natural numbers.
4. (grammar, of a noun) Freely usable with the indefinite article and with numbers, and therefore having a plural form.

Antonyms

• uncountable

Hyponyms

• (having a bijection with a subset): finite
• (having a bijection with a subset): countably infinite

Hypernyms

• (countably infinite): infinite

Derived terms

• countable noun
• countable set

Related terms

• countability

In mathematics, a countable set is a set with the same cardinality (i.e., number of elements) as some subset of the set of natural numbers. The term was originated by Georg Cantor; it stems from the fact that the natural numbers are often called counting numbers. A set that is not countable is called uncountable.

Some authors use countable set to mean a set with the same cardinality as the set of natural numbers. The difference between the two definitions is that under the former, finite sets are also considered to be countable, while under the latter definition, they are not considered to be countable. To resolve this ambiguity, the term at most countable is sometimes used for the former notion, and countably infinite for the latter. The term denumerable is also used to mean countably infinite.