curtail vs shorten

curtail and shorten both are verbs.

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

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

curtail: terminate or abbreviate before its intended or proper end or its full extent
shorten: make shorter than originally intended; reduce or retrench in length or duration

curtail (verb)	shorten (verb)
place restrictions on	become short or shorter
terminate or abbreviate before its intended or proper end or its full extent	make shorter than originally intended; reduce or retrench in length or duration
	reduce in scope while retaining essential elements
	edit by omitting or modifying parts considered indelicate
	make short or shorter