Gyroplane
Gyroplane means a rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving; and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
Source
14 CFR § 1.1
Scoping language
As used in Subchapters A through K of this chapter, unless the context requires otherwise: