'rightfully-obtained' originates from the combination of 'rightfully' and 'obtained'. 'Rightfully' comes from 'right', which has Old English origins in 'riht', meaning 'just' or 'lawful'. 'Obtained' comes from Latin 'obtinere', meaning 'to hold' or 'to possess'.

'Rightfully' evolved from Old English 'rihtlice', and 'obtained' from Latin 'obtinere', through Old French 'obtenir', eventually forming the modern English term 'rightfully-obtained'.

Initially, 'rightfully' meant 'in accordance with justice', and 'obtained' meant 'to hold or possess'. Together, they convey the idea of possessing something in a just manner.