The total demand for finished goods and services in the economy at a given time and price level.

This is the demand for the gross domestic product of a country when inventory levels are static. It is often called effective demand, though at other times this term is distinguished. It is often cited that the aggregate demand curve is downward sloping because at lower price levels a greater quantity is demanded. While this is correct at the microeconomic, single good level, at the aggregate level this is incorrect. The aggregate demand curve is in fact downward sloping as a result of three distinct effects; Pigou's wealth effect the Keynes' interest rate effect and the Mundell-Fleming exchange-rate effect.

Summary:

Everything that is wanted in the market at a certain time