Lewis & Short

gĕlum, i, n., and gĕlus, ūs, m. (nom. gelu, n., Prisc. 658 P.; but only found in Liv. ap. Non. 207, 30, a corrupt passage; and freq. in Vulg., e. g. Dan. 3, 69; Zach. 14, 6: gelum, Lucr. 6, 877; Varr. R. R. 1, 45, 2; gen. geli, Lucr. 5, 205 al.; nom. gelus, Att. ap. Prisc. 6, p. 685 P.; cf. Non. 208, 1, Fragm Trag. v. 390 Rib.; Afran. ap. Non. 207, 32, Com. Fragm. v. 106 Rib.; Cato, R. R. 40, 4 al.; acc. gelum, m., Cat. Orig. 2, Fragm. 30; abl. gelu, m., Mela, 3, 5 ext.; Flor. 4, 12, 18; Plin. Pan. 12) [root γαλ-, to be bright; whence γελάω, to laugh (cf. κυμάτων γέλασμα, Aesch. Pr. 90); γάλα, milk; γαλήνη, calm; cf.: lac, glacies; cf. Curt. Gr. Etym. p. 172], icy coldness, frost, cold (cf.: pruina, glacies, rigor).

  1. I. In gen.: praeusti artus, nive rigentes nervi, membra torrida gelu, Liv. 21, 40, 9: nec ventus fraudi, solve geluve fuit, Ov. de Nuce, 106: et maris adstricto quae coit unda gelu, id. Tr. 2, 196: altitudo gelūs, Plin. 8, 28, 42, § 103: geluque Flumina constiterint acuto, Hor. C. 1, 9, 3: rura gelu tum claudit hiems, Verg. G. 2, 317: horrida cano Bruma gelu, id. ib. 3, 442; Stat. Th. 5, 392.
  2. II. In partic., coldness, chill produced by death, old age, fright, etc. (cf. gelidus, II.; poet.): pectora pigro Stricta gelu, Luc. 4, 653: sed mihi tarda gelu saeclisque effeta senectus, Verg. A. 8, 508; Sen. Troad. 624.