nightmare
night.mare \'ni-t-.ma(*)r, -.me(*)r\ \-ish\ n 1: an evil spirit formerly thought to oppress people during sleep 2: a frightening dream accompanied by a sense of oppression or suffocation that usu. awakens the sleeper 3: an experience, situation, or object having the monstrous character of a nightmare or producing a feeling of anxiety or terror - night.mar.ish aj