Definition 1 of 2
Definition
The rotating assembly of an aircraft, engine, or machine that produces lift, thrust, compression, or electrical output through its motion. In a helicopter, the rotor is the system of rotating blades that generates lift and directional control. In a turbine engine, it is the spinning shaft assembly carrying the compressor and turbine wheels. In a magneto or generator, it is the rotating magnetic component that induces current in the surrounding stationary windings.
Plain English
The spinning part of a machine. In helicopters it's the big set of blades on top. In an engine it's the shaft and wheels that spin inside. In a magneto or generator it's the spinning magnet that produces electrical current.
Context Anchor
Seen in helicopter preflight, rotor-system discussions, and descriptions of rotating parts inside electrical or ignition equipment.
Derivation
From the Latin 'rotare,' meaning 'to turn' or 'to rotate.' Anything called a rotor is, by definition, the part that spins -- as opposed to the stator, which stays still.
Why Pilots Care
Proper rotor function is essential for all helicopter flight; damage or mismanagement can cause loss of control.
Analogy
Like a giant overhead fan that pushes air down hard enough to lift the whole machine.
Intuition Check
Do not assume rotor only means helicopter blades. In aviation, a rotor can also be the spinning part inside a machine such as an alternator or magneto.
Example Sentence 1
Before lifting off, the pilot brought the main rotor up to operating RPM and checked the engine and rotor needles were joined.
Example Sentence 2
As rotor speed increased, the helicopter began to lift off the ground.