Lewis & Short

lĕgĭo, ōnis, f. [2. lego] (prop., a selecting, choosing; hence), transf., a body of soldiers: legio, quod leguntur milites in delectu, Varr. L. L. 5, § 87 Müll.

  1. I. Lit., a Roman legion. It consisted of 10 cohorts of foot-soldiers and 300 cavalry, making together between 4200 and 6000 men. As a general rule, the legion was composed of Roman citizens; it was only on the most pressing occasions that slaves were taken into it. The standard was a silver eagle. The legions were usually designated by numerals, according to the order in which they were levied; though sometimes they were named after the emperor who raised them, or after their leader, after a deity, after some exploit performed by them, etc.: cum legionibus secunda ac tertia, Liv. 10, 18: undevicesima, id. 27, 14: vicesima, id. 27, 38: Claudiana, Tac. H. 2, 84: Galbiana, id. ib. 2, 86: Martia, Cic. Phil. 4, 2: adjutrix, Tac. H. 2, 43: rapax, id. ib.: in legione sunt centuriae sexaginta, manipuli triginta, cohortes decem, Gell. 16, 4, 6; cf. Inscr. Orell. Index rerum, s. v. legio.
  2. II. Transf.
    1. A. Plur., of the troops of other nations, legions, soldiers: Bruttiae Lucanaeque legiones, Liv. 8, 24: Latinae, id. 6, 32; cf. of the troops of the Samnites, id. 10, 17; of the Gauls, id. 22, 14; of the Carthaginians, id. 26, 6: Teleboae ex oppido Legiones educunt suas, Plaut. Am. 1, 1, 62: in quorum (i. e. Thebanorum) sulcis legiones dentibus anguis nascuntur, Juv. 14, 241.
    2. B. In gen., an army, a large body of troops: legio rediit, Enn. ap. Non. 385, 17 (Ann. v. 535 Vahl.): quia cotidie ipse ad me ab legione epistolas mittebat, Plaut. Ep. 1, 1, 56; 83; 2, 2, 22; id. Most. 1, 2, 48: si tu ad legionem bellator cluis, at ego in culina clueo, id. Truc. 2, 7, 53: cetera dum legio campis instructa tenetur, Verg. A. 9, 368: de colle videri poterat legio, id. ib. 8, 605; 10, 120: horruit Argoae legio ratis, Val. Fl. 7, 573.
    3. C. Of a large body of men: idem istuc aliis adscriptivis fieri ad legionem solet, Plaut. Men. 1, 3, 2; cf.: legio mihi nomen est, quod multi sumus, Vulg. Marc. 5, 9; id. Luc. 8, 30; 36: duodecim legiones angelorum, id. Matt. 26, 53.
      1. 2. Trop.: sibi nunc uterque contra legiones parat, his troops, forces, expedients, Plaut. Cas. prol. 50.