Reserve Currency

"A reserve currency is a globally recognized currency held in large quantities by a central bank as part of its foreign exchange reserves. It is widely used to conduct international trade and financial transactions, including investments and debt obligations, eliminating the costs of settling transactions involving different currencies. The U.S. dollar has been the world’s dominant reserve currency since World War II, often functioning as a safe-haven currency during times of economic crises."

Source: https://www.chase.com/personal/investments/learning-and-insights/article/what-is-a-reserve-currency