Gyroplane

A mechanically-driven aeroplane deriving its lift from the reaction of the air on one or more rotors freely rotating in a horizontal plane. This type of aircraft, of which the Autogiro is one example, should be clearly distinguished from the helicopter, in which the rotors are power-driven in normal flight.
Found on http://www.aeroplanemonthly.com/glossary/

Gyroplane

(from the article `helicopter`) ...were two significant steps forward. On September 29, the Breguet brothers, Louis and Jacques, under the guidance of the physiologist and aviation ...
Found on http://www.britannica.com/eb/a-z/g/86

gyroplane

gyroplane 1. 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the fuselage that provides lift for the machine, with forward propulsion being provided by a conventional propeller: superseded in most applications by the helicopter. 2. An aircraft; such as, a helicopter or autogyro, equipped with wings that rotate aroun...
Found on http://www.wordinfo.info/words/index/info/view_unit/946/2

gyroplane

gyroplane: see autogiro.
Found on http://www.infoplease.com/ce6/sci/A0914117.html

GYROPLANE

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, usually a conventional propeller, is independent of the rotor system. Similar to AUTOGYRO.
Found on http://www.aerofiles.com/glossary.html

GYROPLANE

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, usually a conventional propeller, is independent of the rotor system. Similar to AUTOGYRO.
Found on http://www.eaa.org/experimenter/glossary.asp

Gyroplane

A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate
Found on http://www.superglossary.com/Glossary/Technology/Aviation/
No exact match found