Copula
Part of speech: noun
Definition: A word used to link the subject of a sentence with a predicate (usually a subject complement or an adverbial); it serves to unite (or associate) the subject with the predicate. (e.g. be). A function that represents the association between two or more variables, independent of the individual marginal distributions of the variables. (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.
Copulative
Part of speech: adjective
Definition: Of or pertaining to copulationthat acts as a copulathat connects the subject of a clause with its complement