Gyroplane
14 CFR § 1.1 — Definitions
Official definition — 14 CFR Part 1
REGULATION — OFFICIAL DEFINITIONGyroplane 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.
Reproduced verbatim from the eCFR. Regulatory definitions control how the term is used throughout 14 CFR.
Is this a regulation?
Yes — this is regulatory text and is legally binding.
Definition published in 14 CFR Part 1. Regulatory definitions are legally binding wherever the defined term is used in 14 CFR.