(1):

(n.) One to whom is committed some charge, duty, or office, by a superior power; a commissioner.

(2):

(n.) An officer of the bishop, who exercises ecclesiastical jurisdiction in parts of the diocese at a distance from the residence of the bishop.

(3):

(n.) An officer having charge of a special service; as, the commissary of musters.

(4):

(n.) An officer whose business is to provide food for a body of troops or a military post; - officially called commissary of subsistence.