Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
alsĭōsus, a, um, adj. [1. alsius], easily freezing, susceptible to cold: pecus, Varr. R. R. 2, 3, 6: Alsiosa (Habrotonum et Adonium) admodum sunt, Plin 21, 10, 34, § 60.