/aw'teuh juy"roh/ , n. , pl. autogiros .
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the fuselage that provides lift for the machine, with forward propulsion being provided by a conventional propeller: superseded in most applications by the helicopter.
Also, autogyro . Also called gyrocopter, gyroplane .
[ 1920-25; formerly a trademark ]