writing vs knock off

writing is a noun but knock off is not a noun.

Word	Noun	Adjective	Verb	Adverb
writing	Yes	No	No	No
knock off	No	No	Yes	No

writing (noun)	knock off (noun)
the activity of putting something in written form
the act of creating written works
the work of a writer; anything expressed in letters of the alphabet (especially when considered from the point of view of style and effect)
letters or symbols that are written or imprinted on a surface to represent the sounds or words of a language
(usually plural) the collected work of an author

writing (verb)	knock off (verb)
	stop pursuing or acting
	get rid of (someone who may be a threat) by killing
	write quickly
	take by theft
	cut the price of