weakening vs weaken

weakening is a noun but weaken is not a noun.

Word	Noun	Adjective	Verb	Adverb
weakening	Yes	Yes	No	No
weaken	No	No	Yes	No

weakening (noun)	weaken (noun)
the act of reducing the strength of something
becoming weaker

weakening (adjective)	weaken (adjective)
causing debilitation
moderating by making pain or sorrow weaker

weakening (verb)	weaken (verb)
	become weaker
	lessen the strength of
	reduce the level or intensity or size or scope of
	lessen in force or effect
	destroy property or hinder normal operations