calamity vs disaster

calamity and disaster both are nouns.

Word	Noun	Adjective	Verb	Adverb
calamity	Yes	No	No	No
disaster	Yes	No	No	No

As nouns, calamity and disaster are synonyms defined as:

Other synonyms of calamity include cataclysm, catastrophe, tragedy.

calamity (noun)	disaster (noun)
an event resulting in great loss and misfortune	an act that has disastrous consequences
	an event resulting in great loss and misfortune
	a state of extreme (usually irremediable) ruin and misfortune