Entry 2 senses · 2 variants Webster, 1913 Deathly · Death·ly · IPA /ˈdɛθli/ a. adv. 01 a. Deadly; fatal; mortal; destructive. 1. Deadly; fatal; mortal; destructive. 02 adv. Deadly; as, deathly pale or sick. 1. Deadly; as, deathly pale or sick.