[for-eks] –noun
Forex is a commonly used abbreviation for "foreign exchange". It is typically used to describe trading in the foreign exchange market, especially by investors and speculators.
You may not know it, but forex is actually one of the largest markets in the world, with over $4 trillion in average daily volume transacted.
This easily dwarfs the stock market. All the world's stock markets combined average only about $84 billion per day.