tighten vs alter

tighten and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
tighten	No	No	Yes	No
alter	No	No	Yes	No

As verbs, alter is a hypernym of tighten; that is, alter is a word with a broader meaning than tighten:

Other hypernyms of tighten include change, modify.

tighten (verb)	alter (verb)
become tight or tighter	remove the ovaries of
make tight or tighter	become different in some particular way, without permanently losing one's or its former characteristics or essence
severely restrict in scope or extent	cause to change; make different; cause a transformation
narrow or limit	insert words into texts, often falsifying it thereby
	make an alteration to