DEADLY

I. adjective (deadlier; -est) Date: before 12th century likely to cause or capable of producing death , 2. aiming to kill or destroy ; implacable , highly effective , unerring , marked by determination or extreme seriousness, 3. tending to deprive of force or vitality , suggestive of death especially in dullness or lack of animation , very great ; extreme , deadliness noun Synonyms: see: ~ II. adverb Date: before 12th century in a manner to cause death ; mortally , suggesting death, extremely