Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† crĭsĭmus, a, um, adj., = κρίσιμος, decisive, critical: dies, the day of a crisis, in disease, Cael. Aur. Acut. 1, 14, 108; Censor. 14, 9.