plunge vs descend

plunge is a noun but descend is not a noun.

Word	Noun	Adjective	Verb	Adverb
plunge	Yes	No	Yes	No
descend	No	No	Yes	No

As verbs, descend is a hypernym of plunge; that is, descend is a word with a broader meaning than plunge:

Other hypernyms of plunge include come down, fall, go down.

plunge (noun)	descend (noun)
a brief swim in water
a steep and rapid fall

plunge (verb)	descend (verb)
begin with vigor	come as if by falling
devote (oneself) fully to	move downward and lower, but not necessarily all the way
cause to be immersed	do something that one considers to be below one's dignity
immerse briefly into a liquid so as to wet, coat, or saturate	come from; be connected by a relationship of blood, for example
thrust or throw into
fall abruptly
drop steeply
dash violently or with great speed or impetuosity