Plain English Meaning

A small radiator that cools the hot, squeezed air coming from the turbocharger before it goes into the engine. Cooler air is denser, so the engine makes more power and is less likely to suffer damaging knock.

Full Definition

A heat exchanger fitted between the turbocharger (or supercharger) and the engine's induction system that cools the compressed induction air before it enters the cylinders. Compressing air raises its temperature, which reduces its density and increases the risk of detonation; the intercooler removes that added heat by passing the charge air through a core cooled by ram air, restoring density and lowering cylinder head temperatures.