In linguistics, a copula (plural: copulas or copulae) is a word used to link the subject of a sentence with a predicate (a subject complement), such as the word is in the sentence "The sky is blue." The word copula derives from the Latin noun for a "link" or "tie" that connects two different things.
A copula is often a verb or a verb-like word, though this is not universally the case. A verb that is a copula is sometimes called a copulative or copular verb. In English primary education grammar courses, a copula is often called a linking verb. In other languages, copulas show more resemblances to pronouns, as in Classical Chinese and Guarani, or may take the form of suffixes attached to a noun, as in Beja, Ket, and Inuit languages.