What is defined as the system of money in general use in a particular country?

The term that describes the system of money in general use within a particular country is currency. Currency refers to the physical money—coins and paper notes—that is widely accepted as a medium of exchange for goods and services. It serves as the standard unit of value within an economy, facilitating trade and economic transactions.

While the gold standard refers to a monetary system where a country's currency or paper money has a value directly linked to gold, it is not commonly used in modern economies. Commodity money represents physical goods used as currency, such as gold and silver, but it implies a broader category than just the currency in circulation. Credit refers to the ability to borrow money or access goods and services with the promise of future payment, which does not define the system of money itself.

Thus, currency is the most accurate term that encapsulates the concept of the money system used in a specific nation.