Medium of exchange

Medium of exchange is whatever is widely accepted as a method of payment.

Definition

According to Principles of Economics by Timothy Taylor (3rd edition),

Medium of exchange. Whatever is widely accepted as a method of payment.

According to Macroeconomics by Mankiw (7th edition),

Medium of exchange. The item widely accepted in transactions for goods and services; one of the functions of money. (Cf. store of value, unit of account.)