languish vs weaken

languish and weaken both are verbs.

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

As verbs, weaken is a hypernym of languish; that is, weaken is a word with a broader meaning than languish:

languish (verb)	weaken (verb)
become feeble	become weaker
lose vigor, health, or flesh, as through grief	lessen the strength of
have a desire for something or someone who is not present	reduce the level or intensity or size or scope of
	lessen in force or effect
	destroy property or hinder normal operations