hap vs accident

hap and accident both are nouns.

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

As nouns, accident is a hypernym of hap; that is, accident is a word with a broader meaning than hap:

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

Other hypernyms of hap include chance event, fortuity, stroke.

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

hap (verb)	accident (verb)
come to pass