フィアット
Fiat money is a type of currency that is not backed by a commodity, such as gold or silver. It is typically designated by the issuing government to be legal tender, and is authorized by government regulation. Since the end of the Bretton Woods system in 1971, the major currencies in the world are fiat money. 不換紙幣（ふかんしへい）とは、本位貨幣（正貨たる金貨や銀貨）との兌換が保障されていない法定紙幣（英: fiat money）のことをいう。