go off vs hap

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

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

As verbs, hap is a hypernym of go off; that is, hap is a word with a broader meaning than go off:

Other hypernyms of go off include come about, fall out, go on, happen, occur, pass, pass off, take place.

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

go off (verb)	hap (verb)
be discharged or activated	come to pass
happen in a particular manner
burst inward
go off or discharge
stop running, functioning, or operating
run away; usually includes taking something or somebody along