'illegitimately-possessed' originates from the combination of 'illegitimate' and 'possessed', where 'illegitimate' comes from Latin 'illegitimus', meaning 'not lawful', and 'possessed' from Latin 'possessus', meaning 'held or owned'.

'illegitimus' transformed into the Old French 'illégitime', and eventually became the modern English word 'illegitimate'. 'Possessus' transformed into the Old French 'possesser', and eventually became the modern English word 'possess'.

Initially, 'illegitimate' meant 'not lawful', and 'possessed' meant 'held or owned'. The combined term 'illegitimately-possessed' retains the meaning of being unlawfully owned.