Guarantee

A guarantee is a legal agreement in which a person agrees that they will make sure that something is delivered, and if it is not delivered they will be liable. What is to be delivered may be money, or goods, or a performance of some kind, making something happen. Guarantees are common in some sorts of retail sales. Domestic appliances like washing machines or fridges often have a guarantee that they will work for a number of years.

Josiah Wedgwood gave a guarantee that, if a buyer is not satisfied with the product, they could have their money back.