Lewis & Short

Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.

Algĭdum, v. Algidus.

1. algĭdus, a, um, adj. [algeo], cold: algida, sc. regio, Naev. ap. Cic. Or. 45, 152: loca, Cat. 63, 70.
Whence,

2. Algĭdus, i, m., a high snow-capped mountain, and the forest upon it, south-east of Rome, between Tusculum and Velitrœ, now Monte Compatri, Liv. 26, 9, 12; Plin. 18, 13, 34, § 130: gelidus, Hor. C. 1, 21, 6: nivalis, id. ib. 3, 23, 9; id. C. S. 69.
Hence,

  1. I. Algĭdum, i, n., a town upon it, now Pava, Flor. 1, 11.
  2. II. Adj.: Algĭdus, a, um, pertaining to Algidum: terra, Ov. F. 6, 722: secessus, Mart. 10, 30.