Copula

·noun The word which unites the subject and predicate.

II. Copula ·noun The stop which connects the manuals, or the manuals with the pedals;

— called also coupler.

copula
cōpŭla, ae (contr. form cōpla, in Wernsd. Poët. Lat. Min. IV. p. 535), f. [coapio], that which binds...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
copula
cōpula ae, f com-+AP-, a band, rope, thong, tie, fastening : copulā vinctus, N.: Copula detrahitur...

An Elementary Latin Dictionary