opera hat vs hat

opera hat and hat both are nouns.

Word	Noun	Adjective	Verb	Adverb
opera hat	Yes	No	No	No
hat	Yes	No	Yes	No

As nouns, hat is a hypernym of opera hat; that is, hat is a word with a broader meaning than opera hat:

opera hat: a man's hat with a tall crown; usually covered with silk or with beaver fur
hat: headdress that protects the head from bad weather; has shaped crown and usually a brim

Other hypernyms of opera hat include chapeau, lid, man's clothing.

opera hat (noun)	hat (noun)
a man's hat with a tall crown; usually covered with silk or with beaver fur	an informal term for a person's role
	headdress that protects the head from bad weather; has shaped crown and usually a brim

opera hat (verb)	hat (verb)
	put on or wear a hat
	furnish with a hat