Definition
A unit of rotational speed indicating how many full turns a rotating component completes in one minute. In airplanes, RPM most commonly refers to engine crankshaft speed (and, in fixed-pitch propeller aircraft, propeller speed) as displayed on the tachometer.
Plain English
How many times something spins all the way around in a minute. In a plane, it usually means how fast the engine (and propeller) is turning.
Context Anchor
Seen on the engine instruments during takeoff, climbs, slow flight, and performance maneuvers such as a chandelle.
Derivation
From the plain English words 'rotations' (full turns) and 'per minute' (in one minute). Pilots see it written as RPM on the tachometer face and in performance charts.
Why Pilots Care
Correct RPM settings deliver required power while protecting the engine from overspeed damage during climbs, turns, and descents.
Grounding Statement
If the RPM number rises, the engine or propeller is turning faster; if it falls, it is turning slower.
Intuition Check
RPM is not the airplane’s speed through the air. It is the turning speed of the engine or propeller.
Example Sentence 1
The pilot set 2,300 RPM for cruise after leveling off at altitude.
Example Sentence 2
After leveling off, the pilot advanced the throttle to restore cruise RPM.