Lewis & Short

1. caerŭlĕus, and in poetry equally common, caerŭlus, a, um, adj. [cf. cae -sius, κύανος, and Sanscr. cjamas = dark]

  1. I. Lit., dark-colored, dark blue, dark green, cerulean, azure, κυάνεος; poet. epithet of the sky, of the sea, and other similar objects (as dark, opp. albus and marmoreus color, Lucr. 2, 771 sq., and syn. with ater, Verg. A. 3, 64; v. under II. A.).
    1. A. Of the sky: caeli caerula templa, Enn. ap. Cic. Div. 1, 20, 40 (Ann. v. 50 Vahl.); id. ap. Varr, L. L. 7, § 6 Müll. (Ann. v. 66 Vahl.); cf.: (zonae) extremae Caeruleā glacie concretae, Verg. G. 1, 236.
      Also subst.: caerŭla. ōrum, n., Ov. M. 14, 814: per caeli caerula, Lucr. 1, 1089; 6, 96; and without caeli, id. 6, 482.
      Of the universe: magni per caerula mundi, Lucr. 5, 770; and of the brightness of the stars: bigae, Verg. Cir. 37.
      Of mountain heights, Ov. M. 11, 158; cf. candor, Plin. 35, 6, 28, § 47: splendor, id. 37, 9, 51, § 134.
    2. B. Of the sea: ponti plaga caerula, Lucr. 5, 482; cf. id. 2, 772 sq.: pontus, Cat. 36, 11; Ov. M. 13, 838: mare, Cic. Ac. Fragm. ap. Non. p. 162, 30: aequora, Cat. 64, 7; so, campi = mare, Plaut. Trin. 4, 1, 15: aquae, Ov. M. 8, 229; 15, 699: undae, Tib. 1, 3, 37; 1, 4, 45; Varr. ap. Non. p. 254, 21: vada, Verg. A. 7, 198: gurges, Ov. M. 2, 528: color (lacus) caerulo albidi or, viridior et pressior, Plin. Ep. 8, 20, 4: Oceani amictus, Claud. Laud. Stil. 2, 249; App. M. 10, p. 254, 11.
      Also subst.: cae-rŭla, ōrum, n., the sea, the blue surface of the sea: caerula verrunt, Verg. A. 4, 583; 3, 208; 8, 672; Stat. Th. 3, 250.
      Of objects that have relation to the sea: di, sea-deities, Ov. M. 2, 8 sq.: deus, κατ’ .ἐξοχήν, Neptune, Prop. 3 (4), 7, 62; cf. of the same: Jovis frater, Ov. M. 1, 275: Triton, id. ib. 1. 333: Nereus. id. H. 9, 14: Thetis, Tib. 1, 5, 46; and of the same: mater (sc. Achillis), Hor. Epod. 13, 16; Ov. M. 13, 288: Psamathe, a sea-nymph, id. ib. 11, 398: oculi Neptuni. Cic. N. D. 1, 30, 83: currus (Neptuni), Verg. A. 5, 819: equi (Tritonis), Ov. H. 7, 50: Scylla (navis), Verg. A. 5, 123; cf. color. Ov M. 14, 555: puppis, id. F. 2, 112; via. Plaut Rud. 1, 5, 10; Ov. H. 16, 104.
    3. C. Also of rivers and things that are connected therewith: caeruleus Thybris, Verg. A. 8, 64 amnis, Tib. 3, 4, 18; Stat. S. 1, 5, 51: Cydnus. Tib. 1, 7, 14: crines, Ov. M. 5, 432; guttae. id. ib. 5, 633.
    4. D. Of other darkblue objects: omnes se Britanni vitro inficiunt, quod caeruleum efficit colorem, atque hoc horridiores sunt in pugnā aspectu, Caes. B. G. 5, 14: an si caeruleo quaedam sua tempora fuco Tinxerit. idcirco caerula forma bona’st? Prop. 2, 18, 31 sq. (3, 11, 9 sq.); Mart. 11, 53, 1: olearum plaga, Lucr. 5, 1372; draco. Ov. M. 12, 13’ angues, Verg. G. 4, 482; colla, id. A. 2, 381: serpens, Ov. M. 3, 38: guttae (serpentis), id. ib. 4, 578: vestis. Juv. 2. 97: vexillum, Suet. Aug. 25: flos (heliotropi), Plin. 22, 21, 29, § 57: oculi (Germanorum), Tac. G. 4; hence Germania pubes, Hor. Epod. 16, 7.
      Hence, subst.: caerŭlĕum, i, n., a blue color, steel-color, both natural and artificial, Plin. 33, 13, 57, § 161 sq.; 35, 6, 28, § 47; Vitr. 7, 111; 9, 1.
  2. II. Transf.
    1. A. In gen., dark, gloomy, dun, sable, black; poet. epithet of death, the night, rain, etc.: stant Manibus arae Caeruleis moestae vittis, Verg. A. 3, 64 Serv.: imber, id. ib. 3, 194; 5, 10: caeruleus (color) pluviam denuntiat, id. G. 1, 453; so, equi (Plutonis), Ov. F. 4, 446: ratis fati, Prop. 2 (3), 28, 40: puppis (Charontis), Verg. A. 6, 410: mors, Albin. ad Liv. 1, 93: nox, Stat. S. 1, 6, 85: umbra noctis, id. Th. 2, 528; Verg. Cir. 214: panis, Juv. 14, 128: baca (lauri), Plin. 15, 30, 39, § 128: bacis caerula tinus, Ov. M. 10, 98.
    2. B. Dark green, green, greenish: cucumis, Prop. 4 (5), 2, 43: coma, Ov. M. 11, 158: arbor Palladis, id. A. A. 2, 518: campi caerula laetaque prata, Enn. ap. Macr. S. 6, 3.