Plain English Meaning
A piston engine. Pistons move up and down inside cylinders, and that movement is turned into the spinning motion that drives the propeller.
Full Definition
An internal combustion engine in which pistons move back and forth inside cylinders, and that linear motion is converted into rotary motion by a crankshaft to turn the propeller. Fuel and air are burned inside each cylinder, the resulting expansion pushes the piston down, and the crankshaft converts the up-and-down motion into the rotation that drives the propeller.
Context Anchor
Seen in airplane fuel, oil, engine-start, warm-up, and preflight discussions for many training airplanes.
Derivation
From Latin reciprocare, meaning 'to move back and forth.' The name describes exactly what the pistons do — they reciprocate (travel back and forth) inside the cylinders, unlike a turbine engine where parts spin continuously.
Why Pilots Care
Most light training aircraft use reciprocating engines; pilots must understand mixture, throttle, and oil management to operate them safely and avoid engine damage.
Analogy
It works on the same principle as a car engine: pistons going up and down inside cylinders, with a crankshaft turning that motion into rotation. The main difference is that the crankshaft turns a propeller instead of wheels.
Intuition Check
Do not read “reciprocating” as “responding” or “giving back.” In this engine term, it means back-and-forth piston motion.
Example Sentence 1
The Cessna 172 is powered by a four-cylinder reciprocating engine driving a fixed-pitch propeller.
Example Sentence 2
The student adjusted the mixture control to maintain smooth operation of the reciprocating engine at cruise altitude.