thin out vs weaken

thin out and weaken both are verbs.

Word	Noun	Adjective	Verb	Adverb
thin out	No	No	Yes	No
weaken	No	No	Yes	No

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

thin out (verb)	weaken (verb)
make sparse	become weaker
become sparser	lessen the strength of
lessen the strength or flavor of a solution or mixture	reduce the level or intensity or size or scope of
	lessen in force or effect
	destroy property or hinder normal operations