Definition
A unit of rotational speed equal to the number of complete turns a rotating component makes in one minute. In aviation, it most commonly refers to the rotational speed of the engine crankshaft or, in turboprop and turbine engines, the propeller or compressor section.
Plain English
How many times something spins all the way around in one minute.
Context Anchor
Seen on engine instruments, power-setting procedures, aircraft operating handbooks, and instructor discussions about engine operation.
Derivation
Revolution comes from the Latin revolvere, meaning to roll back or turn around. One revolution is one complete turn. Per minute simply tells you the time window over which those turns are counted.
Why Pilots Care
RPM shows available engine power and must stay within limits to avoid damage or insufficient thrust.
Intuition Check
RPM does not mean aircraft speed. It means spinning speed: how fast the engine, propeller, or rotor is turning.
Example Sentence 1
After starting the engine, the pilot let it warm up at 1,000 rpm before advancing the throttle.
Example Sentence 2
During the magneto check the rpm dropped 150 on the left side and recovered when both were selected.