inevitable accident vs disaster

inevitable accident and disaster both are nouns.

Word	Noun	Adjective	Verb	Adverb
inevitable accident	Yes	No	No	No
disaster	Yes	No	No	No

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

inevitable accident: a natural and unavoidable catastrophe that interrupts the expected course of events
disaster: an event resulting in great loss and misfortune

Other hypernyms of inevitable accident include calamity, cataclysm, catastrophe, tragedy.

inevitable accident (noun)	disaster (noun)
a natural and unavoidable catastrophe that interrupts the expected course of events	an act that has disastrous consequences
	an event resulting in great loss and misfortune
	a state of extreme (usually irremediable) ruin and misfortune