Which term refers to the return of a portion of a payment?

The term that refers to the return of a portion of a payment is a rebate. A rebate is a financial incentive provided to consumers, typically as a partial refund of the purchase price after they have made a purchase. This practice is often used to encourage sales by making products more affordable while still maintaining the retailer's or manufacturer's profit margins. Rebates can be issued in various forms, such as cash back, credit towards future purchases, or gift cards.

In contrast, a quantity discount involves reducing the price based on the volume of goods purchased, encouraging bulk buying rather than offering a rebate after purchase. Markup refers to the difference between the cost of a product and its selling price, a method used by retailers to determine pricing strategies. Unit pricing is a method that expresses the price of a product per unit of measure, making it easier for consumers to compare prices of similar items. Each of these terms serves a different purpose in marketing and pricing strategies, highlighting why rebate is the appropriate choice for this question.