'unlawfully-gained' originates from the combination of 'unlawful' and 'gain', where 'unlawful' means 'not conforming to, permitted by, or recognized by law' and 'gain' means 'to obtain or secure something desired'.

'unlawful' changed from the Old English word 'unlagu', meaning 'not according to law', and 'gain' from the Old English 'gægn', meaning 'advantage'.

Initially, 'unlawful' meant 'not according to law', and 'gain' meant 'advantage'. Over time, 'unlawfully-gained' evolved to mean 'obtained in a manner not permitted by law'.