Why this word is great
DAYMARE — [Noun] A vivid, unpleasant mental image experienced while awake, resembling the characteristics of a nightmare. From day ("daytime") + mare ("evil spirit or incubus in folklore, as in nightmare"), modeled after nightmare. Unlike "nightmare" (which unfolds in the helpless theater of sleep) or "daydream" (which drifts on idle whimsy), a daymare is a waking assault of the mind—an intrusion, unbidden. It is the sudden vision of your child stepping into traffic, the phantom sensation of a spider crawling up your neck when nothing is there, or the inexplicable conviction, mid-conversation, that everyone you love is already dead. The horror lies in its clarity: you are awake, and yet the world cracks open.