What word or phrase does your mother always say?
early 15c., "to join," from Latin copulatus, past participle of copulare "join together, couple, bind, link, unite," from copula "band, tie, link," from PIE *ko-ap-, from *ko(m)- "together" + *ap- "to take, reach." Sexual sense attested from 1630s. Related: Copulated; copulating.
copulate cop·u·late (kŏp'yə-lāt')
v. cop·u·lat·ed, cop·u·lat·ing, cop·u·lates
To engage in coitus or sexual intercourse.