Lewis & Short

cālīgĭnōsus (post-class. cālīgōsus, Mart. Cap. 8, § 803; cf. Kopp. ad id. 1, § 67; Ven. Fort. Carm. 5, 4, 25), a, um, adj. [1. caligo],

  1. I. full of mist, covered with mist, dark, obscure, gloomy (rare, but class. in prose and poetry): caelum et umidum et caliginosum, Cic. Tusc. 1, 19, 43: obscurior et quasi caliginosa stella (opp. illustris et pellucida), id. Div. 1, 57, 130: tractus, Plin. 17, 22, 35, § 171: tenebrae, Val. Max. 1, 7, ext. 1.
  2. II. Trop., dark, uncertain, obscure: nox, i. e. an uncertain future, *Hor. C. 3, 29, 30: caliginosissima quaestio, Aug. Ep. 7.
    Comp. and adv. not in use.