Plain English Meaning

It's a piston engine with a built-in air pump that squeezes outside air before sending it into the cylinders. Because the engine drives the pump itself, the engine can keep making strong power higher up where the air is thin.

Full Definition

A piston aircraft engine fitted with a supercharger — an air compressor driven mechanically by the engine crankshaft (typically through gears) — that compresses intake air before it enters the cylinders. This raises manifold pressure and allows the engine to maintain rated power at altitudes where a normally aspirated engine would lose power due to thinner air.

Context Anchor

Seen in discussions, especially when comparing at - airports or on hot days.