noun
autogyro; autogiro
A type of rotorcraft that uses an unpowered rotor for lift and a conventional propeller for thrust. Technical term; not an everyday word.
オートジャイロはヘリコプターと飛行機の中間のような航空機だ。
An autogyro is an aircraft that is like a cross between a helicopter and an airplane.
A helicopter has a powered rotor for both lift and thrust, while an autogyro's rotor is unpowered and spins freely.
Borrowed from English 'autogyro', itself coined from Greek 'auto-' (self) and 'gyro' (circle, rotation).