off vs bump off

off is an adjective but bump off is not an adjective.

Word	Noun	Adjective	Verb	Adverb
off	No	Yes	Yes	Yes
bump off	No	No	Yes	No

As verbs, off and bump off are synonyms defined as:

Other synonyms of off include dispatch, hit, murder, polish off, remove, slay.

off (adjective)	bump off (adjective)
not in operation or operational
(of events) no longer planned or scheduled
not performing or scheduled for duties
in an unpalatable state
below a satisfactory level

off (verb)	bump off (verb)
kill intentionally and with premeditation	kill intentionally and with premeditation

off (adverb)	bump off (adverb)
at a distance in space or time
from a particular thing or place or position (`forth' is obsolete)
no longer on or in contact or attached