The term "buck" is a colloquial expression commonly used to refer to the United States dollar, often abbreviated as USD. It is widely recognized in everyday conversation and is used in various contexts, such as shopping, banking, and financial discussions. The origin of the term dates back to the 18th century when deer skins, or "bucks," were used as a medium of exchange. In addition to the USD, the term "buck" can also refer to other currencies in informal settings, particularly in countries like Canada, where the Canadian dollar is sometimes called a "loonie." The use of "buck" reflects a casual approach to discussing money and is understood by many people across different regions.