'wrongfully-gained' originates from the combination of 'wrongfully,' meaning 'in a manner that is not right or just,' and 'gained,' meaning 'obtained or acquired.'

The term 'wrongfully-gained' evolved from the Old English 'wrang' meaning 'injustice' and 'gained' from the Old French 'gaigner,' meaning 'to earn or win.'

Initially, it meant 'obtained through injustice,' and this meaning has largely remained the same in modern usage.