set back vs setback

set back is not a noun while setback is a noun.

Word	Noun	Adjective	Verb	Adverb
set back	No	No	Yes	No
setback	Yes	No	No	No

set back (noun)	setback (noun)
	an unfortunate happening that hinders or impedes; something that is thwarting or frustrating

set back (verb)	setback (verb)
slow down the progress of; hinder
cost a certain amount
hold back to a later time