-asis, suffix
L. -ăsis, Gr. -ᾱσις, forming names of diseases, really nouns of state or process from verbs in -άειν; as from ϕθείρ louse, ϕθειρά-ειν to be lousy, ϕθειρίᾱσις phthiˈriăsis; so elephantiasis, psoriasis, and many modern words, more or less analogical, as allantiasis, arseniasis, etc.