I.a thick atmosphere, a mist, vapor, fog (mostly poet. or in post-Aug. prose): “suffundere caelum caligine,” Lucr. 6, 479; 6, 461; 6, 92: “(ignis) piceă crassus caligine,” Verg. G. 2, 309; cf. id. A. 9, 36; Liv. 29, 27, 7: “densa caligo occaecaverat diem,” id. 33, 7, 2; cf. Suet. Ner. 19: “fumidam a terră exhalari caliginem,” Plin. 2, 42, 42, § 111: “caligo aestuosa,” Col. 11, 2, 53 (for which, id. 11, 2, 57: “nebulosus aestus): pruinae et caligo,” id. 3, 2, 4; cf. Pall. Febr. 9, 2.—Also in plur.: “inter caligines,” Col. 3, 1, 7.—Hence,
II. Transf.
A. (Causa pro effectu.) Darkness, obscurity, gloom (produced by mist, fog, etc.; freq. with tenebrae; “class. in prose and poetry): mi ob oculos caligo obstitit, Plaut Mil. 2, 4, 51: cum altitudo caliginem oculis obfudisset,” i. e. had caused dizziness, Liv. 26, 45, 3: “erat in tantā calligine major usus aurium quam oculorum,” id. 22, 5, 3 Weissenb.: noctem insequentem eadem calligc obtinuit; “sole orto est discussa,” id. 29, 27, 7: “nox terram caligine texit,” Lucr. 6, 853; 5, 649: “caeca noctis,” id. 4, 457: “caecae umbra,” id. 3, 305; cf. Verg. A. 3, 203: “quam simul agnorunt inter caliginis umbras,” Ov. M. 4, 455: “ara obscurā caligine tecta,” Cic. Arat. 194.—With tenebrae, Cic. Agr. 2, 17, 44; Curt. 9, 4, 18; Lampr. Comm. 16.—In later writers also with a gen.: “caligo tenebrarum,” Quint. Decl. 18, 7; cf. Sen. Agam. 472 Heins.; “and inversely: tenebris illunae caliginis impeditus,” App. M. 9, p. 214.—
B. Trop.
1. In gen., mental blindness, dulness of perception: “quod videbam equidem, sed quasi per caliginem: praestrinxerat aciem animi D. Bruti salus,” Cic. Phil. 12, 2, 3; so id. Fin. 5, 15, 43: adhuc tamen per caliginem video, Plin. Ep. 5, 8, 8: caecā mentem caligine consitus, * Cat. 64, 207: “Augustus... omnibus omnium gentium viris magnitudine suā inducturus caliginem,” to throw into the shade, Vell. 2, 37, 1. —
2. Of dark, difficult circumstances, calamity, affliction, gloom: “vide nunc caliginem temporum illorum,” Cic. Planc. 40, 96: “superioris anni,” id. post Red. in Sen. 3, 5: “an qui etesiis, qui per cursum rectum regnum tenere non potuerunt, nunc caecis tenebris et caligine se Alexandriam perventuros arbitrati sunt?” id. Agr. 2, 17, 44: “illa omnis pecunia latuit in illā caligine ac tenebris, quae totam rem publicam tum occuparant,” Cic. Verr. 2, 3, 76, § 177: “ecce illa tempestas, caligo bonorum, tenebrae rei publicae,” id. Prov. Cons. 18, 43: “tantum caliginis, tantum perturbationis offusum,” Plin. Ep. 3, 9, 16: “quaedam scelerum offusa caligo,” Quint. 9, 3, 47.—
C. In medic. lang., as a disease of the eyes, dim-sightedness, weakness of the eyes, Cels. 6, 6, n. 32; Plin. 20, 7, 26, § 61; 20, 23, 95, § 254; 25, 13, 92, § 144; 32, 9, 31, § 97; 34, 11, 27, § 114; Scrib. Comp. 179.