'illicitly' originates from Latin, specifically the word 'illicitus,' where 'in-' meant 'not' and 'licitus' meant 'lawful.' 'Claimed' comes from the Latin word 'clamare,' meaning 'to call out.'

'Illicitus' transformed into the Old French word 'illicite,' and eventually became the modern English word 'illicit.' 'Clamare' evolved into the Old French 'clamer,' which became 'claim' in Middle English.

Initially, 'illicit' meant 'not allowed by law,' and this meaning has largely remained the same in modern usage.