crash dive vs descent

crash dive and descent both are nouns.

Word	Noun	Adjective	Verb	Adverb
crash dive	Yes	No	No	No
descent	Yes	No	No	No

As nouns, descent is a hypernym of crash dive; that is, descent is a word with a broader meaning than crash dive:

crash dive (noun)	descent (noun)
a rapid descent by a submarine	the act of changing your location in a downward direction
	properties attributable to your ancestry
	a movement downward
	the hereditary derivation of an individual
	a downward slope or bend
	the kinship relation between an individual and the individual's progenitors