adjective, dead·li·er, dead·li·est.
- deadly nightshade,
- deadly sins,
Origin of deadly
Examples from the Web for deadliness
We are not talking about an end to spree killing, only about a (perhaps) very slight reduction in its deadliness.There's Little We Can Do to Prevent Another Massacre|Megan McArdle|December 17, 2012|DAILY BEAST
This time she spoke to him in the voice with the quality of deadliness in it which she had used to her mother.T. Tembarom|Frances Hodgson Burnett
But the knowledge of his deadliness kept him from being made a target.When the West Was Young|Frederick R. Bechdolt
Missiles have peculiar characteristics, and differ in their capacity for deadliness.South Africa and the Transvaal War, Vol. IV (of 6)|Louis Creswicke
adjective -lier or -liest
Old English deadlic "mortal, subject to death," also "causing death;" see dead + -ly (1). Meaning "having the capacity to kill" is from late 14c. (Old English words for this included deaðbærlic, deaðberende).