'repayment' originates from Latin and Old French elements, specifically the prefix 're-' (from Latin) and Old French 'paiement', where 're-' meant 'back/again' and 'paiement' ultimately comes from Latin 'pagare' meaning 'to pay'.

'repayment' developed in Middle English as the combination of the prefix 're-' with Old French 'paiement' (payment) and evolved into the modern English word 'repayment'.

Initially it meant 'a paying back' or 'the act of paying back', and over time it has retained that core meaning while also being used for the individual amounts (installments) that are paid.