backfire vs hap

backfire and hap both are nouns.

Word	Noun	Adjective	Verb	Adverb
backfire	Yes	No	Yes	No
hap	Yes	No	Yes	No

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

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

backfire (noun)	hap (noun)
a miscalculation that recoils on its maker	an accidental happening
a loud noise made by the explosion of fuel in the manifold or exhaust of an internal combustion engine
the backward escape of gases and unburned gunpowder after a gun is fired
a fire that is set intentionally in order to slow an approaching forest fire or grassfire by clearing a burned area in its path

backfire (verb)	hap (verb)
set a controlled fire to halt an advancing forest to prairie fire	come to pass
emit a loud noise as a result of undergoing a backfire
come back to the originator of an action with an undesired effect