deadly

Universal Words adjective, adverb adjective (deadlier, deadliest) HELPNOTE More deadly and deadliest are the usual forms. You can also use most deadly. 1 causing or likely to cause death: a deadly weapon / disease * deadly poison * The cobra is one of the world's deadliest snakes. * The terrorists have chosen to play a deadly game with the civilian population. * the seven deadly sins (= for which you could be sent to HELL) 2 [onlybeforenoun] extreme; complete: I'm in deadly earnest. * We sat in deadly silence. * They are deadly enemies (= will always remain enemies, and are full of hatred for each other). 3 extremely effective, so that no defence is possible: His aim is deadly (= so accurate that he can kill easily). * It was the deadly striker's 11th goal of the season. 4 (BrE, informal) very boring: The lecture was absolutely deadly. adverb 1 (informal) extremely: deadly serious / dull 2 (rare) = DEATHLY: deadly pale / cold