accident vs hap

accident and hap both are nouns.

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

As nouns, hap is a hyponym of accident; that is, hap is a word with a more specific, narrower meaning than accident:

accident: anything that happens suddenly or by chance without an apparent cause
hap: an accidental happening

Other hyponyms of accident include break, good luck, happy chance, coincidence, happenstance, lottery.

accident (noun)	hap (noun)
anything that happens suddenly or by chance without an apparent cause	an accidental happening
an unfortunate mishap; especially one causing damage or injury

accident (verb)	hap (verb)
	come to pass