DEFINITION of 'International Currency Exchange Rate'. The rate at which two currencies in the market can be exchanged. International currency exchange rates display how much of one unit of a currency can be exchanged for another currency.or example, for a U.S. investor, knowing the dollar to euro exchange rate is valuable when choosing European investments. A declining U.S. dollar could increase the value of foreign investments, just as an increasing U.S. dollar value could hurt the value of foreign investments. RELATED TERMS.