chapeau vs sou'wester

chapeau and sou'wester both are nouns.

Word	Noun	Adjective	Verb	Adverb
chapeau	Yes	No	No	No
sou'wester	Yes	No	No	No

As nouns, sou'wester is a hyponym of chapeau; that is, sou'wester is a word with a more specific, narrower meaning than chapeau:

chapeau: headdress that protects the head from bad weather; has shaped crown and usually a brim
sou'wester: waterproof hat with wide slanting brim longer in back than in front

chapeau (noun)	sou'wester (noun)
headdress that protects the head from bad weather; has shaped crown and usually a brim	waterproof hat with wide slanting brim longer in back than in front
	a strong wind from the southwest