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."
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:
Half the story is told from Julia’s point of view; the other half is set in the nightmare world of Bernie’s brain—which isn’t as dead as the company suggests.
From The Wall Street Journal ● Jul. 15, 2026
Every successful actor probably has a nightmare that one day the phone stops ringing and you’re coasting on fading glory.
From Los Angeles Times ● Jul. 6, 2026
Until last weekend, the World Cup had mostly been a refuge from the nightmare that is American politics.
From Slate ● Jul. 6, 2026
Peter Bonetti, an outstanding keeper for Chelsea, stepped in and had a nightmare.
From BBC ● Jul. 5, 2026
"O God, please let this be only a nightmare," he prayed.
From "Adventures of Don Quixote" by Argentina Palacios
The last five years have come at a cost to Angharad, who experienced nightmares and still feels angry and distrustful of others.
From BBC ● Jul. 8, 2026
It’s a sea of nightmares in suits, and among them is Schlossberg, the Dennis the Menace we don’t deserve, don’t really want, but are burdened with regardless.
From Slate ● Jun. 18, 2026
Winston has nightmares about how his youngest brother is being treated.
From Los Angeles Times ● Jun. 17, 2026
While Mr. Harris dreamed up a singular literary terror, Stephen King has countless nightmares to his name.
From The Wall Street Journal ● May 29, 2026
Things were so much easier back then, when nightmares were only in dreams.
From "How to Disappear Completely" by Ali Standish
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.
