What is an AIRPLANE anyway?

Here is what my dictionary says:

AIRPLANE Definition & Usage Examples | Dictionary.com

noun


a heavier-than-air aircraft kept aloft by the upward thrust exerted by the passing air on its fixed wings and driven by propellers, jet propulsion, etc.

b any similar heavier-than-air aircraft, as a glider or helicopter.


What troubles me is including HELICOPTER or GLIDER within the definition. I was in an army attack helicopter unit back in the 1990's and was curious even then as to why personnel in that unit sometimes referred to choppers as AIRPLANES.

Whenever somebody utters AIRPLANE in my ears, only fixed-wing self-powered flying machines come to mind.

Also, how did the term AIRPLANE even come into existence? Why did the inventors choose this term? The word has Latin and Greek roots. What do the meaning of the root words in AIRPLANE actually have to do with how this self-powered fixed-wing aerodyne actually operates?