trĭbūnus, i, m. [tribus, prop. the chief of a tribe; hence, in gen.], a chieftain, commander, tribune.
I Tribuni aerarii, paymasters , who assisted the quaestors, Cato ap. Gell. 7, 10, 2; cf. Varr. L. L. 5, § 181 Müll.; Fest. p. 2 ib.; called also tribuni aeris, Plin. 33, 2, 7, § 31. By the Lex Aurelia these tribuni aerarii were made judges on the part of the people: (Milonem) tribuni aerarii condemnarunt, Cic. Q. Fr. 2, 6, 6; id. Cat. 4, 7, 15: a tribunis aerariis absolutus, id. ib. 2, 16, 3; cf. in a pun with aerati (rich), id. Att. 1, 16, 8. This judicial office was taken from them by Julius Caesar, Suet. Caes. 41.—
II Tribuni Celerum, captains or commanders of the Celeres, Liv. 1, 59, 7; cf. Dig. 1, 2, 2, § 15; Weissenb. ad Liv. 1, 15, 8. —
III Tribuni militares or militum, tribunes of the soldiers , military tribunes; these were officers of the army, six to each legion, who commanded in turn, each two months at a time: qui M. Aemilio legati et praefecti et tribuni militares fuerunt, Cic. Clu. 36, 99; so, militares, Plin. 34, 3, 6, § 11; cf. in sing.: cum tribunus militaris depugnavi apud Thermopylas, Cic. Sen. 10, 32: a tribunis militum, praefectis reliquisque, qui, etc., Caes. B. G. 1, 39; so, militum, id. ib. 3, 7; cf. in sing.: tribunus militum, id. ib. 3, 5; Cic. Fam. 15, 4, 2: tribuni cohortium, Caes. B. C. 2, 20.— Sing. : Stilonius Priscus qui tribunus cohortis, sub Classico fuerat, Plin. Ep. 3, 9, 18; cf.: tribunus minor, Veg. Mil. 2, 7; and tribunus legionis, Val. Max. 3, 2, 20.—
IV Tribuni militum consulari potestate, military tribunes with consular power; these were the highest officers of the State from A.U.C. 310 to A.U.C. 388. They were chosen from the patrician and plebeian orders, and were at first three, then six, and, after the year 352, eight in number, Liv. 4, 6, 8; 4, 7, 1; 5, 1, 2; called tribuni consulares, id. 8, 33; Becker, Antiq. 2, 2, p. 136 sq.—
V Tribuni plebis, and more freq. simply tribuni, tribunes of the people , whose office it was to defend the rights and interests of the Roman plebeians against the encroachments of the patricians, Liv. 2, 33, 2; 2, 56, 3 sq.; Cic. Rep. 2, 33, 58 sq.; id. Leg. 3, 7, 16; cf. Becker, Antiq. 2, 2, p. 247 sq.; Lange, Antiq. 1, 1, p. 592 sq., and the authorities cited by both.