adjective

causing or able to cause death.

a deadly weapon

fatal,lethal,mortal,death-dealing,life-threatening,dangerous,destructive,injurious,harmful,pernicious,detrimental,deleterious,unhealthy,noxious,toxic,poisonous,terminal,incurable,untreatable,malignant,deathly,nocuous,mephitic,baneful

adverb

in a way resembling or suggesting death; as if dead.

her skin was deadly pale

deathly,deathlike,ashen,ghostly,white,pallid,wan,pale,ghastly