Mate1  —n. 1 friend or fellow worker. 2 colloq. Form of address, esp. To another man. 3 a each of a breeding pair, esp. Of birds. B colloq. Partner in marriage. C (in comb.) Fellow member or joint occupant of (team-mate; room-mate). 4 officer on a merchant ship. 5 assistant to a skilled worker (plumber's mate). —v. (-ting) (often foll. By with) 1 come or bring together for breeding. 2 mech. Fit well. [low german]