kill off vs exterminate

kill off and exterminate both are verbs.

Word	Noun	Adjective	Verb	Adverb
kill off	No	No	Yes	No
exterminate	No	No	Yes	No

As verbs, kill off and exterminate are synonyms defined as:

kill off and exterminate: kill en masse; kill on a large scale; kill many

kill off (verb)	exterminate (verb)
kill en masse; kill on a large scale; kill many	kill en masse; kill on a large scale; kill many
	destroy completely, as if down to the roots