I don't know which one of LB or IAAL the following supports, but here goes. (hahaha)
From Roget's Thesaurus, third edition, printed August 1998:
Mate: n. 1. one of a pair, duplicate, match, twin, counterpart, companion, equivalent. 2. one of a pair of mated animals; spouse, partner, consort, helpmate; husband, (informal) hubby; wife, better half. 3. (British informal) chum, pal, crony, buddy, friend, companion, comrade, sidekick; coworker, fellow worker, associate, confederate, colleague, partner; classmate; roommate; messmate. 4. first mate, second mate; ship's officer below the rank of captain, master mariner.
v. 5. pair off; couple, copulate, cohabit