loosen vs weaken

loosen and weaken both are verbs.

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

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

loosen (verb)	weaken (verb)
become loose or looser or less tight	become weaker
make loose or looser	lessen the strength of
make less dense	reduce the level or intensity or size or scope of
disentangle and raise the fibers of	lessen in force or effect
cause to become loose	destroy property or hinder normal operations
become less severe or strict
make less severe or strict