accident vs crash

accident and crash both are nouns.

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

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

Other hyponyms of accident include collision, wreck, accidental injury, injury, shipwreck, wreck, casualty, fatal accident.

accident (noun)	crash (noun)
anything that happens suddenly or by chance without an apparent cause	the act of colliding with something
an unfortunate mishap; especially one causing damage or injury	a serious accident (usually involving one or more vehicles)
	a loud resonant repeating noise
	a sudden large decline of business or the prices of stocks (especially one that causes additional failures)
	(computer science) an event that causes a computer system to become inoperative

accident (verb)	crash (verb)
	sleep in a convenient place
	stop operating
	undergo a sudden and severe downturn
	undergo damage or destruction on impact
	break violently or noisily; smash
	cause to crash
	hurl or thrust violently
	enter uninvited; informal
	move with, or as if with, a crashing noise
	fall or come down violently
	move violently as through a barrier
	make a sudden loud sound
	occupy, usually uninvited