nightmare
Americannoun
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nightmares
plural
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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."
Synonym Usage
See dream.
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of nightmare
Middle English word dating back to 1250–1300; see origin at night, mare 2
Explanation
If you wake with a start after a terrifying dream, you've had a nightmare. A nightmare is not just a bad dream — it's seriously scary or upsetting. You can also use nightmare to describe something terrible that happens during the day. Your run-in with a skunk in your back yard might be a nightmare, for example, or your humiliating experience forgetting your lines in a play. In the late thirteenth century, a nightmare was "an evil female spirit afflicting sleepers with a feeling of suffocation," from the Old English word mare, "incubus or goblin."
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.
See Examples For:
But it would take a nightmare for Golesh’s coaching dreams to come true.
From The Wall Street Journal ● Aug. 27, 2026
GTA 6 leaks - a nightmare or a blip for the biggest video game of the year?
From BBC ● Aug. 26, 2026
Jackson flags this exact relationship in her dissent, as the court’s new ruling Monday “lets another shoe drop in the Kafkaesque nightmare that our precedents have been steadily creating for certain plaintiffs.”
From Slate ● Aug. 25, 2026
The post has 10 million views. , externalComments describe it as "nightmare fuel" and "genuinely haunting", suggesting it had been pulled from a 'cursed attic'.
From BBC ● Aug. 23, 2026
In terms of a spreading epidemic, Farmer and Goldfarb knew this was a nightmare.
From "Mountains Beyond Mountains" by Tracy Kidder and Michael French
Curry, who died Tuesday at 80, made a gleefully evil turn as a clown that sparked nightmares for legions of Gen X and millennial viewers that continue to haunt to this day.
From Los Angeles Times ● Aug. 26, 2026
Edwards recalled being told by a psychologist to think about birthday parties when he had nightmares, despite many of the children who attended those parties having died.
From BBC ● Aug. 10, 2026
They also often do little to relieve the nightmares themselves.
From Science Daily ● Aug. 6, 2026
At one point, amid the bewildering turmoil, one of the Politburo members simply shakes his head and says: “I’ve had nightmares that made more sense than this.”
From The Wall Street Journal ● Aug. 3, 2026
The sight of a stern judge demanding a book from him had been the stuff of his nightmares since childhood.
From "The Long-Lost Home" by Maryrose Wood
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.
