CURRENCY, money in actual use in a country. Ex. Coins and paper money are currency in the United States.

TRADE or TRADING, the act or process of buying and selling; exchange of goods; commerce. Ex. wholesale trade, retail trade, domestic trade. The United States has much trade with foreign countries.

COURSE, OR coursing. onward movement; forward progress; advance. Ex. (Figurative.) the course of events. They slackened their course (Samuel Johnson). (Figurative.) Our history book traces the course of man's development from the cave to modern city living.
A series of studies in a school, college, or university. A student must complete a certain course in order to graduate.