straighten vs alter

straighten and alter both are verbs.

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

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

Other hypernyms of straighten include change, modify.

straighten (verb)	alter (verb)
put (things or places) in order	remove the ovaries of
make straight or straighter	become different in some particular way, without permanently losing one's or its former characteristics or essence
make straight	cause to change; make different; cause a transformation
straighten by unrolling	insert words into texts, often falsifying it thereby
straighten up or out; make straight	make an alteration to
get up from a sitting or slouching position