What is another word for "mate"?

Roget's Thesaurus (1911) lists these synonyms for "mate": abettor, accessory, accompaniment, accompany, accomplice, acquaintance, addition, adherent, adjunct, adjutant, adjuvant, advocate, after, all, ally, along, alter, ambo, amigo, and, angel, appendage, appurtenance, arm, assistant, associate, associated, association, attend, attendant, attribute, auxiliary, backer, bear, bedfellow, best, biformity, binary, binate, binomial.