copula

noun, plural cop·u·las, cop·u·lae [kop-yuh-lee] /ˈkɒp yəˌli/.

1. something that connects or links together.
2. Also called linking verb. Grammar. a verb, as be, seem, or look, that serves as a connecting link or establishes an identity between subject and complement.Compare action verb.
3. Logic. a word or set of words that acts as a connecting link between the subject and predicate of a proposition.

noun plural -las or -lae (-ˌliː)

1. a verb, such as be, seem, or taste, that is used merely to identify or link the subject with the complement of a sentence. Copulas may serve to link nouns (or pronouns), as in he became king, nouns (or pronouns) and adjectival complements, as in sugar tastes sweet, or nouns (or pronouns) and adverbial complements, as in John is in jail
2. anything that serves as a link
3. logic the often unexpressed link between the subject and predicate terms of a categorial proposition, as are in all men are mortal

n.

1. A narrow part connecting two structures.