top hat vs hat

top hat and hat both are nouns.

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

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

top 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 top hat include chapeau, lid, man's clothing.

top 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

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