Lewis & Short

āla, ae, f. [for axla, contr. from axilla, Cic. Or. 45, 153; cf. ἄγχος = ὦμος (Hesych.) = shoulder = O. H. Germ. Ahsala; Germ. Achsel].

  1. I. Lit., a wing, as of a bird: galli plausu premunt alas, Enn. ap. Cic. Div. 2, 26; Verg. A. 3, 226 al.: Me. Vox mihi ad aurīs advolavit. So. Ne ego homo infelix fui, qui non alas intervelli, that I did not pluck off its wings, Plaut. Am. 1, 1, 170.
    Poet., of the gods: Mors atris circumvolat alis, Hor. S. 2, 1, 58: volucris Fati Tardavit alas, id. C. 2, 17, 25: bibulae Cupidinis alae, Ov. A. A. 1, 233: furvis circumdatus alis Somnus, Tib. 2, 1, 89: me jocundis Sopor impulit alis, Prop. 1, 3, 45: Madidis Notus evolat alis, Ov. M. 1, 264.
    Of sails: velorum pandimus alas, Verg. A. 3, 520.
    Of oars: classis centenis remiget alis, Prop. 4, 6, 47: remigium alarum, Verg. A. 1, 301 (cf. Hom. Od. 11, 125); so inversely remi is used of wings: super fluctus alarum insistere remis, Ov. M. 5, 558 (cf. πτεροῖς ἐρέσσει, Eur. Iphig. Taur. 289; Aeschyl. Agam. 52; and cf. Lucr. 6, 743).
    Of wind and lightning: Nisus Emicat et ventis et fulminis ocior alis, Verg. A. 5, 319 al.
  2. II. Transf.
    1. A. In man, the upper and under part of the arm, where it unites with the shoulder; the armpit, Liv. 9, 41; 30, 34: aliquid sub alā portare, Hor. Ep. 1, 13, 12: hirquinae, Plaut. Poen. 4, 2, 51: hirsutae, Hor. Epod. 12, 5: halitus oris et alarum vitia, Plin. 21, 20, 83, § 142: virus alarum et sudores, id. 35, 15, 52, § 185: sudor alarum, Petr. 128 (many Romans were accustomed to pluck out the hair from the armpits, Sen. Ep. 114; Juv. 11, 157; v. alipilus).
    2. B. In animals, the hollow where the foreleg is joined to the shoulder; the shoulder-blade.
      Of elephants, Plin. 11, 40, 95, § 324.
      Of frogs, Plin. 9, 51, 74, § 159.
    3. C. In trees and plants, the hollow where the branch unites with the stem, Plin. 16, 7, 10, § 29; so id. 22, 18, 21, § 45; 25, 5, 18, § 38 al.
    4. D. In buildings, the wings, the side apartments on the right and left of the court, the side halls or porches, the colonnades; called also in Gr. πτερά, Vitr. 6, 4, 137; 4, 7, 92.
    5. E. In milit. lang., the wing of an army (thus conceived of as a bird of prey), commonly composed of the Roman cavalry and the troops of the allies, esp. their horsemen; hence, alarii in contrast with legionarii, and separated from them in enumeration, also having a leader, called praefectus alae, Tac. H. 2, 59 al.; cf. Lips. de Milit. Rom. 1, 10 Manut.; Cic. Fam. 2, 17 fin.; Herz. ad Caes. B. G. 1, 51; Smith, Dict. Antiq.; Cincius ap. Gell. 16, 4, 6; cf. Gell. 10, 9, 1: Alae, equites: ob hoc alae dicti, quia pedites tegunt alarum vice, Serv. ad Verg. A. 4, 121: peditatu, equitibus atque alis cum hostium legionibus pugnavit, Cato ap. Gell. 15, 9, 5; Cic. Off. 2, 13, 45: dextera ala (in alas divisum socialem exercitum habebat) in primā acie locata est, Liv. 31, 21; Vell. 2, 117 al.
      An ala, as a military division, usu. consisted of about 500 men, Liv. 10, 29.
      Note: Such alae gave names to several towns, since they were either levied from them, quartered in them, or, after the expiration of their time of service, received the lands of such towns.
      So, Ala Flaviana, Ala Nova, et saep. (cf. castrum, II. 1. fin.).