[aw-tuh-jahy-roh] 
| an aircraft with an unpowered, horizontally rotating propeller on a shaft above the fuselage that provides lift for the machine, with forward propulsion being provided by a conventional propeller: superseded in most applications by the helicopter. |
| au·to·gi·ro also au·to·gy·ro (ô'tō-jī'rō) n. pl. au·to·gi·ros also au·to·gy·ros An aircraft powered by a conventional propeller and supported in flight by a freewheeling, horizontal rotor that provides lift. [Originally a trademark.] |
autogiro
rotary-wing aircraft, superseded after World War II by the more efficient helicopter. It employed a propeller for forward motion and a freely rotating, unmotorized rotor for lift. In searching for an aircraft that could be slowed down in flight and landed vertically, experimenters built many prototypes that were difficult to control in flight
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təˈdʒaɪ