"unjust, wicked," 1670s, from iniquity + -ous. Earlier were iniquous (1650s, from Latin iniquus) and inique (1520s, from French inique). Related: Iniquitously; iniquitousness.
Entries linking to iniquitous
iniquity n.
c. 1300, "hostility, malevolence; a hostile action," from Old French iniquité, iniquiteit "wickedness; unfavorable situation" (12c.), from Latin iniquitatem (nominative iniquitas) "unequalness, unevenness," figuratively "unfavorableness, unfairness, injustice," noun of quality from iniquus "unjust, unequal; slanting, steep," from in- "not" (see in- (1)) + aequus "just, equal" (see equal (adj.)).
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.
-ous
word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."