Synonyms for mate

noun

1. One of a pair

   complement, analog, counterpart; see match 2.

2. A companion

   partner, comrade, schoolfellow, stable companion, helpmate, playmate, classmate, buddy*, pal*, chum*, roomie*; see also friend 1.

3. A marriage partner

   spouse, bride, groom, bedmate, the old man*, the old lady*; see also husband, wife.

4. A naval officer

   warrant officer, skipper, petty officer, next in command to a captain, first mate, second mate, third mate, boatswain's mate; see also officer 3.