rarefy vs weaken

rarefy and weaken both are verbs.

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

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

rarefy (verb)	weaken (verb)
weaken the consistency of (a chemical substance)	become weaker
make more subtle or refined	lessen the strength of
lessen the density or solidity of	reduce the level or intensity or size or scope of
	lessen in force or effect
	destroy property or hinder normal operations