seamount vs mountain

seamount and mountain both are nouns.

Word	Noun	Adjective	Verb	Adverb
seamount	Yes	No	No	No
mountain	Yes	No	No	No

As nouns, mountain is a hypernym of seamount; that is, mountain is a word with a broader meaning than seamount:

seamount: an underwater mountain rising above the ocean floor
mountain: a land mass that projects well above its surroundings; higher than a hill

Other hypernyms of seamount include mount.

seamount (noun)	mountain (noun)
an underwater mountain rising above the ocean floor	a land mass that projects well above its surroundings; higher than a hill
	(often followed by `of') a large number or amount or extent