flatten vs alter

flatten and alter both are verbs.

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

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

Other hypernyms of flatten include change, modify.

flatten (verb)	alter (verb)
become flat or flatter	remove the ovaries of
make flat or flatter	become different in some particular way, without permanently losing one's or its former characteristics or essence
lower the pitch of (musical notes)	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to