inevitable accident vs tragedy

inevitable accident and tragedy both are nouns.

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

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

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

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

inevitable accident (noun)	tragedy (noun)
a natural and unavoidable catastrophe that interrupts the expected course of events	drama in which the protagonist is overcome by some superior force or circumstance; excites terror or pity
	an event resulting in great loss and misfortune