Final answer:
The term for the price of one's country's currency expressed in terms of another's is the currency exchange rate, essential for GDP comparisons.
Step-by-step explanation:
The price of one country's currency expressed in terms of another country's currency is called the currency exchange rate. Currency exchange rates are crucial for comparing Gross Domestic Product (GDP) among countries with different currencies.
They are determined by the supply and demand in foreign exchange markets and can be expressed in various ways, such as the amount of one currency needed to purchase a unit of another currency. There are two main types of exchange rates: market exchange rates, which fluctuate daily, and purchasing power parity (PPP), which is used for longstanding international comparisons of GDP.