Iniquity, n.; pl. Iniquities.
Etymology: [OE. iniquitee, F. iniquité, L. iniquitas, inequality, unfairness, injustice. See Iniquous.]
1. Absence of, or deviation from, just dealing; want of rectitude or uprightness; gross injustice; unrighteousness; wickedness; as, the iniquity of bribery; the iniquity of an unjust judge. Till the world from his perfection fell Into all filth and foul iniquity. Spenser.
2. An iniquitous act or thing; a deed of injustice o Milton. Your iniquities have separated between you and your God. Is. lix. 2.
3. A character or personification in the old English moralities, or moral dramas, having the name sometimes of one vice and sometimes of another. See Vice. Acts old Iniquity, and in the fit Of miming gets the opinion of a wit. B. Jonson.
Shades of meaning
Fernald has no entry of its own for iniquity; he lists it under abomination, injustice, sin.
Where he writes about it:
Iniquity, in the original sense, is a want of or a deviation from equity; but it is now applied in the widest sense to any form of ill-doing. — from injustice