Meaning

adjective causing or capable of causing death

adjective of an instrument of certain death

adjective extremely poisonous or injurious; producing venom

originFrom Middle English dedly, dedlych, dedlich, from Old English dēadlīċ (adjective), from Proto-West Germanic *dauþalīk, from Proto-Germanic *dauþalīkaz (“deadly”, literally “deathly”). By surface analysis, dead + -ly. Cognate with Saterland Frisian dodelk (“deadly”), West Frisian deadlik (“deadly”), Dutch dodelijk (“deadly”), German tödlich (“deadly”), Swedish dödlig (“deadly, fatal, mortal”),…

Etymology from Wiktionary, CC BY-SA 3.0