Lewis & Short

algeo, alsi, 2, v. n. [acc. to Fest. from ἀλγέω = to feel pain; cf. ἄλγος, algor, and algus], to be cold, to feel cold; cf. Consent. 2051 P. (opp. aestuare; accordingly a subjective coldness; while frigere, opp. calere, is objective, Doed. Syn. 3, 89): si algebis, tremes, Naev. ap. Cic. de Or. 2, 71, 286: erudiunt juventutem, algendo, aestuando, Cic. Tusc. 2, 14, 34: sudavit et alsit, Hor. A. P. 413: algentis manus est calfacienda sinu, Ov. A. A. 2, 214.
Poet.: algentes togae, i. e. so torn to pieces, that those who wear them must suffer from cold, Mart. 12, 36.
Trop.: probitas laudatur et alget, virtue is praised, and yet freezes, i. e. is not cherished, is neglected, Juv. 1, 74.
Hence, algens, P. a., in the post-Aug. per., = algidus and frigidus, cold: pruinae, Stat. Th. 3, 469: loca, Plin. 14, 2, 4, § 27; 16, 10, 19, § 46.