deadly - adjective

• causing or capable of causing death
• of an instrument of certain death
• extremely poisonous or injurious; producing venom
• involving loss of divine grace or spiritual death
• exceedingly harmful
• (of a disease) having a rapid course and violent effect

deadly - adverb

• as if dead
• (used as intensives) extremely

deadly - thesaurus

baneful   deathly   deucedly   devilishly   insanely   lethal   lifelessly   madly   mortal   pernicious   pestilent   venomous   virulent