MATE (a corruption of make, from O. Eng. gemaca, a " comrade ")  , a companion . In the language of the sea, the mate is the companion or assistant of the master, or of any officer at the head of a division of the crew . In the merchant service the mates are the officers who serve under the master, commonly called the captain, navigate the vessel under his direction, and replace him if he dies, or is disabled . In a war-ship mates serve under the gunner, boatswain, carpenter, &c . They are officers told off to attend to a particular part of the ship, as for example mate of the upper deck, whose duty is to see that it iS kept clean, or mate of the hold, who is employed to serve out the water and other stores, and to keep the weights adjusted so as to preserve the trim—or balance—of the ship .