chapeau vs headgear

chapeau and headgear both are nouns.

Word	Noun	Adjective	Verb	Adverb
chapeau	Yes	No	No	No
headgear	Yes	No	No	No

As nouns, headgear is a hypernym of chapeau; that is, headgear is a word with a broader meaning than chapeau:

chapeau: headdress that protects the head from bad weather; has shaped crown and usually a brim
headgear: clothing for the head

Other hypernyms of chapeau include headdress.

chapeau (noun)	headgear (noun)
headdress that protects the head from bad weather; has shaped crown and usually a brim	clothing for the head
	stable gear consisting of any part of a harness that fits about the horse's head
	the hoist at the pithead of a mine