subsidence vs subside

subsidence is a noun but subside is not a noun.

Word	Noun	Adjective	Verb	Adverb
subsidence	Yes	No	No	No
subside	No	No	Yes	No

subsidence (noun)	subside (noun)
a gradual sinking to a lower level
the sudden collapse of something into a hollow beneath it
an abatement in intensity or degree (as in the manifestations of a disease)

subsidence (verb)	subside (verb)
	wear off or die down
	sink down or precipitate
	sink to a lower level or form a depression
	descend into or as if into some soft substance or place