Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
noun pl. autogiros
an aircraft that moves forward by means of a propeller and is supported in the air mainly by means of a large rotor mounted horizontally above the fuselage and turned by air pressure rather than motor power: largely superseded by the helicopter
Origin: Sp, orig. a trademark, Autogiro < auto-, auto- + Gr gyros, a circle: see gyrate
Used by arrangement with John Wiley & Sons, Inc.
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
also au·to·gy·ronoun 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.
Origin: Originally a trademark.