Plain English Meaning
An aircraft that flies because it has spinning rotor blades on top (or elsewhere) that produce lift, instead of fixed wings.
Full Definition
A heavier-than-air aircraft that depends principally on its lift from the lift generated by one or more rotors.
Context Anchor
Seen in FAA rules, aircraft category descriptions, pilot certificate requirements, and discussions of helicopters and gyroplanes.
Derivation
From 'rotor' (a rotating part) and 'craft' (a vehicle). The name simply describes the defining feature: an aircraft whose lift comes from rotating blades rather than fixed wings.
Why Pilots Care
Rotorcraft follow distinct certification, training, and flight rules from airplanes, affecting pilot certificates, , and -site requirements.