One entry found for nightmare.
Main Entry: night·mare
Pronunciation: nt-ma()r, -me()r
Etymology: Middle English nightmare "evil spirit thought to haunt people during sleep," from night "night" and mare "spirit," from Old English mare "evil spirit haunting people in sleep" 1: a frightening dream 2: a frightening or horrible experience - night·mar·ish /-ish/ adjective Word History In the Middle Ages many people believed in a type of evil spirit that was said to haunt people while they slept. Such a demon was known in Old English as a mare. Because it was believed to come in the night, it later became known in Middle English as a nightmare. It was not until the 16th century that the word nightmare came to mean "a frightening dream." This meaning probably came from the belief that such dreams were caused by evil spirits.