Mixed economy: An economic system in which both the government and private enterprise play important roles with regard to production, consumption, investment, and savings.

Monetary policy: Federal Reserve System actions to influence the availability and cost of money and credit as a means of helping to promote high employment, economic growth, price stability, and a sustainable pattern of international transactions.

Money supply: The amount of money (coins, paper currency, and checking accounts) that is in circulation in the economy.

Monopoly: The sole seller of a good or service in a market.

Mutual fund: An investment company that continually offers new shares and buys existing shares back on demand and uses its capital to invest in diversified securities of other companies. Money is collected from individuals and invested on their behalf in varied portfolios of stocks.