Deathly means resembling death or suggesting the presence of death. When something is deathly pale, it looks as white and lifeless as a corpse. When a room falls deathly silent, the quiet becomes so complete and unsettling that it feels like the silence of a graveyard.

The word intensifies whatever it describes by connecting it to death's extremeness. A deathly cold winter is dangerously, bone-chillingly frigid, the kind of cold that could actually kill someone caught outside without shelter. A crowd might become deathly still when waiting for important news, frozen in a way that feels almost supernatural.

Writers often use deathly to create atmosphere in scary stories. A character might hear deathly footsteps echoing down a dark hallway, or notice a deathly odor seeping from an abandoned building. The word tells readers something feels wrong, threatening, or deeply unnatural.

You can also be deathly afraid of something, meaning your fear runs so deep it almost paralyzes you. Someone deathly afraid of heights might freeze completely at the top of a tall ladder, unable to move up or down.

As an adverb, deathly can also mean “extremely,” especially in phrases like deathly tired or deathly serious.