Other forms: daymares
A daymare is a waking nightmare — a horrifying experience or vividly intrusive thought that occurs while you're wide awake.
Daymare is a play on nightmare, in which the Old English mare refers to a spirit or goblin thought to sit on sleepers' chests, smothering them. A daymare brings that same sense of suffocating dread into the light of day. A daymare can be a literal waking hallucination, a vivid "what-if" scenario running through your mind, or a real-world disaster that feels too awful to be true. A daymare is any waking moment that leaves you desperate to "wake up."