'deadly' definitions:

Definition of 'deadly'

(from WordNet)
adverb
As if dead [syn: deadly, lifelessly]
adverb
(used as intensives) extremely; "she was madly in love"; "deadly dull"; "deadly earnest"; "deucedly clever"; "insanely jealous" [syn: madly, insanely, deadly, deucedly, devilishly]
adjective
Causing or capable of causing death; "a fatal accident"; "a deadly enemy"; "mortal combat"; "a mortal illness" [syn: deadly, deathly, mortal]
adjective
Of an instrument of certain death; "deadly poisons"; "lethal weapon"; "a lethal injection" [syn: deadly, lethal]
adjective
Extremely poisonous or injurious; producing venom; "venomous snakes"; "a virulent insect bite" [syn: deadly, venomous, virulent]
adjective
Involving loss of divine grace or spiritual death; "the seven deadly sins" [syn: deadly, mortal(a)]
adjective
Exceedingly harmful [syn: baneful, deadly, pernicious, pestilent]
adjective
(of a disease) having a rapid course and violent effect

Definition of 'deadly'

From: GCIDE
  • deadly \dead"ly\, a.
  • 1. Capable of causing death; mortal; fatal; destructive; certain or likely to cause death; as, a deadly blow or wound. [1913 Webster]
  • 2. Aiming or willing to destroy; implacable; desperately hostile; flagitious; as, deadly enemies. [1913 Webster]
  • Thy assailant is quick, skillful, and deadly. --Shak. [1913 Webster]
  • 3. Subject to death; mortal. [Obs.] [1913 Webster]
  • The image of a deadly man. --Wyclif (Rom. i. 23). [1913 Webster]
  • Deadly nightshade (Bot.), a poisonous plant; belladonna. See under Nightshade. [1913 Webster]

Definition of 'deadly'

From: GCIDE
  • deadly \dead"ly\, adv.
  • 1. In a manner resembling, or as if produced by, death; deathly. "Deadly pale." --Shak. [1913 Webster]
  • 2. In a manner to occasion death; mortally. [1913 Webster]
  • The groanings of a deadly wounded man. --Ezek. xxx. 24. [1913 Webster]
  • 3. In an implacable manner; destructively. [1913 Webster]
  • 4. Extremely. [Obs.] "Deadly weary." --Orrery. "So deadly cunning a man." --Arbuthnot. [1913 Webster]

Synonyms of 'deadly'

From: Moby Thesaurus