In linguistics, a copula is a word used to link the subject of a sentence with a predicate (a subject complement or an adverbial). Although it might not itself express an action or condition, it serves to equate (or associate) the subject with the predicate. The word 'copula' originates from the Latin noun for a "link or tie" that connects two different things (for a short history of the copula see the appendix to Moro 1997 and references cited there). The use of copulas is known as copulation.

A copula is sometimes (though not always) a verb or a verb-like part of speech. In English primary education grammar courses, a copula is often called a linking verb.

The term is generally used to refer to the main copular verb in the language: in the case of English, this is "to be". It can also be used to refer to all such verbs in the language: in that case, English copulas include "to be", "to become", "to get", "to feel", and "to seem". Other verbs have secondary uses as copulative verbs, as fall in "The zebra fell victim to the lion."

For a complete list see: List of English copulae.