An exchanger is a person or device that trades one thing for another. At a currency exchange office, the exchanger is the person who swaps your dollars for euros or yen when you travel to another country. They calculate the current exchange rate and give you the right amount of foreign money.

The word also appears in technical contexts. A heat exchanger is a device that transfers warmth from one liquid or gas to another without mixing them, like the radiator in a car that moves heat from the engine to the air. Scientists and engineers use exchangers to move energy or materials efficiently from one place to another.

You might also call someone an exchanger if they're in the business of trading goods: an exchanger of baseball cards, for instance, or an exchanger of stamps. The word emphasizes the back-and-forth nature of the transaction. Unlike simply buying or selling, exchanging means both sides give up something and receive something in return.