Plain English Meaning
How many full turns something makes every minute. In an aircraft, it usually tells you how fast the engine or propeller is spinning.
Full Definition
A unit of rotational speed expressing the number of complete turns a rotating component makes in one minute. In aviation, RPM most commonly refers to the rotational speed of an engine's crankshaft or a propeller, and is displayed on the tachometer in the cockpit.
Context Anchor
Seen on engine instruments, aircraft checklists, operating handbooks, and instructor explanations when setting or checking engine speed.
Derivation
From Latin 'revolvere' (to turn back, roll around) — the same root as 'revolve.' A revolution is one complete turn. 'Per minute' simply sets the time window for counting those turns.