'iniquity' originates from Latin, specifically the word 'iniquitas,' where 'in-' meant 'not' and 'aequus' meant 'equal or just.'

'iniquitas' transformed into the Old French word 'iniquité,' and eventually became the modern English word 'iniquity' through Middle English.

Initially, it meant 'unfairness or inequality,' but over time it evolved into its current meaning of 'wickedness or immoral act.'