nightmare

noun

night·​mare ˈnīt-ˌmer How to pronounce nightmare (audio)
1
: an evil spirit formerly thought to oppress people during sleep
2
: a frightening dream that usually awakens the sleeper
3
: something (such as an experience, situation, or object) having the monstrous character of a nightmare or producing a feeling of anxiety or terror
nightmare adjective
nightmarish adjective
nightmarishly adverb

Did you know?

Looking at nightmare, you might guess that it is a compound formed from night and mare. If so, your guess is correct. But while the night in nightmare makes sense, the mare part is less obvious. Most English speakers know mare as a word for a female horse or similar equine animal, but the mare of nightmare is a different word, an obsolete one referring to an evil spirit that was once thought to produce feelings of suffocation in people while they slept. By the 14th century the mare was also known as nightmare, and by the late 16th century nightmare was also being applied to the feelings of distress caused by the spirit, and then to frightening or unpleasant dreams.

Examples of nightmare in a Sentence

Mommy, I had a really scary nightmare. The party was a complete nightmare.
Recent Examples on the Web Then, after one particularly intense nightmare involving confessional booths, endless hallways and grasping hands, Cecilia goes to the infirmary. David Fear, Rolling Stone, 20 Mar. 2024 Soon Cecilia starts having nightmares and has weird experiences with some of the nuns. Bill Goodykoontz, The Arizona Republic, 18 Mar. 2024 Surviving an inexplicable nightmare with only his wits keeping him alive, Greste was sentenced to seven years in jail, but was released in 2015. Patrick Frater, Variety, 14 Mar. 2024 But this week’s uproar over a manipulated photo has turned the royal fairy tale into a public-relations nightmare for the family. Sydney Lake, Fortune, 13 Mar. 2024 That’s a great model for Purdy and a possible nightmare for the Niners. Dieter Kurtenbach, The Mercury News, 12 Mar. 2024 The annual event celebrating the worst that Hollywood had to offer in the previous year was swept by the public domain waking nightmare, Winnie-the-Pooh: Blood and Honey, winning five Golden Raspberries. Lester Fabian Brathwaite, EW.com, 9 Mar. 2024 Zuckerberg sold us on a social-media dream that turned out to be a nightmare. Ross Andersen, The Atlantic, 7 Mar. 2024 What happened inside that school was truly a nightmare come to life, but ... Gina Kaufman, Detroit Free Press, 7 Mar. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'nightmare.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Middle English nyghte mare, from nyghte night entry 1 + mare mare entry 3

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of nightmare was in the 14th century

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Dictionary Entries Near nightmare

Cite this Entry

“Nightmare.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nightmare. Accessed 29 Mar. 2024.

Kids Definition

nightmare

noun
night·​mare ˈnīt-ˌma(ə)r How to pronounce nightmare (audio)
-ˌme(ə)r
1
: a frightening dream
2
: a frightening or horrible experience
nightmarish adjective
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"

Word Origin
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.

Medical Definition

nightmare

noun
: a frightening or distressing dream that usually awakens the sleeper

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