autogiro vs autogyro

autogiro and autogyro both are nouns.

Word	Noun	Adjective	Verb	Adverb
autogiro	Yes	No	No	No
autogyro	Yes	No	No	No

As nouns, autogiro and autogyro are synonyms defined as:

autogiro and autogyro: an aircraft that is supported in flight by unpowered rotating horizontal wings (or blades); forward propulsion is provided by a conventional propeller

Other synonyms of autogiro include gyroplane.

autogiro (noun)	autogyro (noun)
an aircraft that is supported in flight by unpowered rotating horizontal wings (or blades); forward propulsion is provided by a conventional propeller	an aircraft that is supported in flight by unpowered rotating horizontal wings (or blades); forward propulsion is provided by a conventional propeller