fatal vs deathly

fatal and deathly both are adjectives.

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

fatal (adjective)	deathly (adjective)
bringing death	having the physical appearance of death
having momentous consequences; of decisive importance	causing or capable of causing death
controlled or decreed by fate; predetermined
(of events) having extremely unfortunate or dire consequences; bringing ruin

fatal (adverb)	deathly (adverb)
	to a degree resembling death
	to an extreme degree