shorten vs alter

shorten and alter both are verbs.

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

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

Other hypernyms of shorten include change, modify.

shorten (verb)	alter (verb)
become short or shorter	remove the ovaries of
make shorter than originally intended; reduce or retrench in length or duration	become different in some particular way, without permanently losing one's or its former characteristics or essence
reduce in scope while retaining essential elements	cause to change; make different; cause a transformation
edit by omitting or modifying parts considered indelicate	insert words into texts, often falsifying it thereby
make short or shorter	make an alteration to