inundation vs mountain

inundation and mountain both are nouns.

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

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

inundation (noun)	mountain (noun)
the rising of a body of water and its overflowing onto normally dry land	a land mass that projects well above its surroundings; higher than a hill
an overwhelming number or amount	(often followed by `of') a large number or amount or extent