c.1300, "hostility, malevolence; a hostile action," from Old French iniquité "wickedness, unfavorable situation," from Latin iniquitatem (nominative iniquitas) "unequalness, unevenness, injustice," noun of quality from iniquus "unjust, unequal; slanting, steep," from in- "not" (see in-(1)) + aequus "just, equal" (see equal, adj.). For vowel change, see acquisition. Meaning "evil, wickedness" is from late 14c.