"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.
early 15c., perversite, "wickedness," from Old French perversité "depravity, degeneracy" (12c.), from Latin perversitatem (nominative perversitas) "forwardness, untowardness," from perversus (see perverse). From 1520s as "perverse character, disposition, or conduct."
For the vowel change in the Latin compound, see acquisition. Meaning "evil, wickedness" is from late 14c. Old Iniquity (1610s) was a comic or buffoonish character in old morality plays, representing vice.