Repayment is the act of paying back money that you borrowed, or returning a favor someone did for you. Most often you will meet this word in the context of loans and debt — 'monthly loan repayments', 'the repayment period is five years' — talking about the schedule or amount you must pay back over time. Less often, but still real, people talk about 'repayment' for kindness — repaying someone's help with help of your own, though 'repay' by itself is more common than 'repayment' in that emotional sense.