the action of returning or retaliating to something, especially the action of repaying something in the form of revenge;
e.g. He is plotting what he will do to them as payback for humiliating him.
(noun)
the reward, returns, or repayment to be obtained from some investment, especially in a financial sense, with the profit equal to the initial amount invested, or the time taken for these returns to be earned;
e.g. This venture has a short time for payback, since you can quickly make a profit from it.