lighten vs alter

lighten and alter both are verbs.

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

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

Other hypernyms of lighten include change, modify.

lighten (verb)	alter (verb)
make more cheerful through the use of color	remove the ovaries of
become lighter	become different in some particular way, without permanently losing one's or its former characteristics or essence
alleviate or remove (pressure or stress) or make less oppressive	cause to change; make different; cause a transformation
become more cheerful	insert words into texts, often falsifying it thereby
reduce the weight on; make lighter	make an alteration to
make more cheerful