commissarius

Commissarius, commissarii, m. Second declension, and a medieval word rather than a classical one. It is built from committo, to entrust, plus the agent suffix -arius, so a commissarius is literally a man to whom a matter has been committed.

Church and chancery Latin use it constantly for a delegate acting on a bishop's or a prince's authority within a fixed brief, and that brief is the point: the office exists only for the business named in the commission. Do not read the later senses backwards into it. There is no quartermaster here and no party official, only a deputy with a warrant. It gives commissary, commissioner and French commissaire.