One who shares an office with another

plural of office mate

(chess) The quickest possible checkmate in the game of chess.

plural of first mate

(nautical) An officer on a merchant ship next in rank to the captain and responsible to the captain for the safety and security of the ship.

(politics) A candidate on a joint ticket. / (politics) A candidate for the US vice-presidency. / One of a pair of ships with coordinated, often reciprocal, sailing schedules.

(baseball) One who plays in the same battery, either the pitcher or the catcher.

Alternative spelling of teammate

plural of team-mate

(psychology, genetics) Between males and females of a species, the mutual attraction or selection, for reproductive purposes, of individuals with similar characteristics.