late 14c., depraven, "corrupt, lead astray, pervert," from Old French depraver "to pervert; accuse" (14c.) and directly from Latin depravare "distort, disfigure;" figuratively "to pervert, seduce, corrupt," from de- "completely" (see de-) + pravus "crooked," which is of unknown etymology. Related: Depraved; depraving.
word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).
Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]
"depravity, evil or corrupt state, wickedness," 1540s, from Latin pravitas "crookedness, distortion, deformity; impropriety, perverseness," from pravus "wrong, bad," literally "crooked," a word of unknown etymology.
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Harper, D. (n.d.). Etymology of depravity. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/depravity