set off vs hap

set off is not a noun while hap is a noun.

Word	Noun	Adjective	Verb	Adverb
set off	No	No	Yes	No
hap	Yes	No	Yes	No

set off (noun)	hap (noun)
	an accidental happening

set off (verb)	hap (verb)
cause to burst with a violent release of energy	come to pass
set in motion or cause to begin
direct attention to, as if by means of contrast
provoke or stir up
put in motion or move to act
depart for someplace
make up for