fatal vs disastrous

fatal and disastrous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
fatal	No	Yes	No	No
disastrous	No	Yes	No	No

As adjectives, fatal and disastrous are synonyms defined as:

fatal and disastrous: (of events) having extremely unfortunate or dire consequences; bringing ruin

Other synonyms of fatal include black, calamitous, fateful.

fatal (adjective)	disastrous (adjective)
bringing death	(of events) having extremely unfortunate or dire consequences; bringing ruin
having momentous consequences; of decisive importance
controlled or decreed by fate; predetermined
(of events) having extremely unfortunate or dire consequences; bringing ruin