nightmare
Americannoun
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a terrifying dream in which the dreamer experiences feelings of helplessness, extreme anxiety, sorrow, etc.
- Synonyms:
- phantasmagoria
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a condition, thought, or experience suggestive of a nightmare.
the nightmare of his years in prison.
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(formerly) a monster or evil spirit believed to oppress persons during sleep.
noun
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a terrifying or deeply distressing dream
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an event or condition resembling a terrifying dream
the nightmare of shipwreck
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( as modifier )
a nightmare drive
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a thing that is feared
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(formerly) an evil spirit supposed to harass or suffocate sleeping people
Usage
Where does the word nightmare come from? Nightmares are scary and unpleasant. But you can rest easy knowing that the fascinating origin of the word nightmare makes it clear humans have been having them for hundreds of years.In Old English, a mare was a kind of evil or cursed spirit. Mares appear in all kinds of folklore, including German and Slavic stories. Mares were said to ride on people's chests at night, causing suffocation and bad dreams. These mares, often female, were known as nightmares (because they came at night).By the 16th century, the word nightmare came to refer to a sensation of suffocation or anxiety during sleep, and now simply a bad dream. While nightmares are terrifying, there is good news: at least most of us don't worry about evil spirits trying to suffocate us in our sleep anymore.The roots of these other words may get a rise—of laughter or surprise—out of you. Run on over to our roundup of them at "Weird Word Origins That Will Make Your Family Laugh."
Related Words
See dream.
Other Word Forms
- nightmarish adjective
- nightmarishly adverb
- nightmarishness noun
Etymology
Origin of nightmare
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Det Ch Insp Louise Metcalfe, leading the Essex Police investigation, said the author of the anonymous handwritten letter to officers "seemed reticent of coming forward but couldn't bear the nightmare of knowing what they knew".
From BBC • Apr. 2, 2026
Bucknor’s nightmare week continued when he left a game after a foul tip hit him in the face mask.
From Los Angeles Times • Apr. 1, 2026
Which means that anything resembling 2012 could be a nightmare for America’s richest and most popular sport.
From The Wall Street Journal • Mar. 31, 2026
Barbie Dream Fest is bit of a pink nightmare.
From MarketWatch • Mar. 30, 2026
The ferocious winter bear from his nightmare flashed into Jackson’s mind.
From "I Survived the Great Alaska Earthquake, 1964" by Lauren Tarshis
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
