Lewis Short
(adjective) : ad-algÄdus, a, um, ad, intens.
* Very cold, chilly; of climate: adalgidum maxime,Fronto, Ep. ad M. Caes. 2, 9, p. 54 Mai; in Naev. ap. Cic. Or. 45, 152, Clussman would read adalgidum for atque algidum (B. and K.).
Charlton T. Lewis, Charles Short, A Latin Dictionary