Plain English Meaning
An aircraft engine that uses pistons sliding up and down inside cylinders to spin the propeller. It works on the same basic principle as a car engine.
Full Definition
An internal-combustion engine used in aircraft in which pistons move back and forth inside cylinders, with that linear motion converted by a crankshaft into rotary motion that turns the propeller. Fuel and air are burned inside each cylinder in a repeating cycle of intake, compression, power, and exhaust strokes.
Context Anchor
Seen in aircraft systems, , , and discussions, especially for small training airplanes.