Lewis & Short

1. āter, tra, trum, adj. [cf. αἴθω, to burn; Sanscr. idh; αἴθων αἰθήρ, Αἴτνη, Aetna, aether, aestus, aestas] (pr. burnt black, black as a coal; cf.: Tam excoctam reddam atque atram quam carbost, Ter. Ad. 5, 3, 63: hence), black; and specif., coalblack, lustreless-black, sable, dark (opp. albus, lustreless-white, and diff. from niger, glossy black, v. albus init.; class. and freq., but never in Vulg., which uses niger).

  1. I. Lit.: album an atrum vinum potas? Plaut. Men. 5, 5, 17: atrior multo Quam Aegyptii, id. Poen. 5, 5, 11: alba et atra discernere non poterat, Cic. Tusc. 5, 39, 114: nigra scuta, tincta corpora; atras ad proelia noctes legunt, Tac. G. 43: Mos erat antiquus niveis atrisque capillis, etc., Ov. M. 15, 41; so id. ib. 15, 44; cf. albus: fauces, Lucr. 6, 1147: dens, Hor. Epod. 8, 3: nubes, Lucr. 6, 180; Hor. C. 2, 16, 2: lumen, with smoke, Verg. A. 7, 457: agmen, with dust, id. ib. 12, 450 Serv.: axis, with blood, Sil. 2, 186: Eridanus ater stragibus, id. 6, 107: bilis, Plaut. Capt. 3, 4, 64, and Cic. Tusc. 3, 5, 11 (cf. the Gr. μελαγχολία): cruor, Hor. Epod. 17, 31: tempestas, Lucr. 6, 258 sq.; Verg. A. 5, 693: hiemps, id. ib. 7, 214: canis, Ter. Phorm. 4, 4, 25: corvus atro gutture, Cat. 108, 5: venena, Verg. G. 2, 130: Tartara, Lucr. 3, 966; so, Cocytus, Hor. C. 2, 14, 17: mare, dark, stormy, id. S. 2, 2, 16: fluctus, Verg. A. 5, 2: mons, v. 2. ater.
    The proverb albus an ater, v. albus.
    Poet., = atratus, clothed in black: lictores, Hor. Ep. 1, 7, 6; cf. albus, I. B. 2.
  2. II. Trop.
    1. A. In gen., black, dark, gloomy, sad, dismal, unfortunate, etc.: funus, Lucr. 2, 580: formido, id. 4 [173], and id. 6, 254; so, Timor, Verg. A. 9, 719: cupressus, id. ib. 3, 64: dies, id. ib. 6, 429; Prop. 3, 2, 4: mors, Hor. C. 1, 28, 13: fila trium sororum, id. ib. 2, 3, 16: Esquiliae (as a burying-place), dismal, id. S. 2, 6, 32: seu mors atris circumvolat alis, id. ib. 2, 1, 58: cura, id. C. 3, 1, 40; 3, 14, 13; 4, 11, 35: lites, id. A. P. 423: comes, id. S. 2, 7, 115: serpens, Verg. G. 1, 129; Ov. M. 3, 63 al.: genius .. vultu mutabilis, albus et ater, Hor. Ep. 2, 2, 189.
      In Roman civil life, dies atri are the days on which the state experienced some calamity, unlucky days. (This designation is said to have arisen from the Roman custom of marking every unfortunate day in the calendar with coal); Varr. L. L. 6, § 29; Liv. 6, 1; Gell. 5, 17; Fest. s. v. nonarum, p. 179 Müll.; id. s. v. religiosus, p. 278 Müll.; Ov. A. A. 1, 418; Macr. S. 1, 15 fin. and 16; Afran. ap. Non. p. 73, 33: si atro die faxit insciens, probe factum esto, Liv. 22, 10.
    2. B. Esp.
      1. 1. Rare and poet., of mind or feeling, malevolent, malicious, virulent (cf. niger, II. D., and the Gr. μέλας, II. 4 Lidd. and Scott): versus, Hor. Ep. 1, 19, 30: si quis atro dente me petiverit, id. Epod. 6, 15.
      2. 2. Also poet. of something difficult to be understood, dark, obscure (so μέλας, Anth. Pal. 11, 347): latebrae Lycophronis atri, Stat. p. 5, 3, 157.
        Comp. v. supra, I.
        Sup. and adv. not used.