tophus vs crust

tophus and crust both are nouns.

Word	Noun	Adjective	Verb	Adverb
tophus	Yes	No	No	No
crust	Yes	No	Yes	No

As nouns, crust is a hypernym of tophus; that is, crust is a word with a broader meaning than tophus:

Other hypernyms of tophus include encrustation, incrustation.

tophus (noun)	crust (noun)
an incrustation that forms on the teeth and gums	the trait of being rude and impertinent; inclined to take liberties
a deposit of urates around a joint or in the external ear; diagnostic of advanced or chronic gout	the outer layer of the Earth
	a hard outer layer that covers something

tophus (verb)	crust (verb)
	form a crust or form into a crust