(linguistics, grammar) A word, usually a verb, used to link the subject of a sentence with a predicate (usually a subject complement or an adverbial), that unites or associates the subject with the predicate.

(statistics) A function that represents the association between two or more variables, independent of the individual marginal distributions of the variables.

(music) A device that connects two or more keyboards of an organ.

(biology) The act of copulation; mating.