/nuyt"mair'/ , n.
1. a terrifying dream in which the dreamer experiences feelings of helplessness, extreme anxiety, sorrow, etc.
2. a condition, thought, or experience suggestive of a nightmare: the nightmare of his years in prison.
3. (formerly) a monster or evil spirit believed to oppress persons during sleep.
[ 1250-1300; ME; see NIGHT, MARE 2 ]
Syn. 1. phantasmagoria. See dream .