knock off vs cut back

knock off and cut back both are verbs.

Word	Noun	Adjective	Verb	Adverb
knock off	No	No	Yes	No
cut back	No	No	Yes	No

As verbs, cut back is a hypernym of knock off; that is, cut back is a word with a broader meaning than knock off:

Other hypernyms of knock off include bring down, cut, cut down, reduce, trim, trim back, trim down.

knock off (verb)	cut back (verb)
stop pursuing or acting	place restrictions on
get rid of (someone who may be a threat) by killing	cut down on; make a reduction in
write quickly	cultivate, tend, and cut back the growth of
take by theft	return in time
cut the price of