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:
It hasn’t been the nightmare pairing so many predicted — at least not for opponents.
From Los Angeles Times ● Aug. 17, 2026
She is overwhelmed by memories of other nightmare disasters, such as the massive earthquake that shook the same region in 1999 and left nearly 1,200 dead.
From Barron's ● Aug. 11, 2026
He had lost his mother during this sentence, but he had finally begun to put his life together before this nightmare struck.
From Slate ● Aug. 11, 2026
But Mr. Robinson’s cogent point is that a nightmare can take many forms.
From The Wall Street Journal ● Aug. 7, 2026
But this was no nightmare; it was real, and it was getting closer.
From "The Wild Robot Escapes" by Peter Brown
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
"You have no idea the nightmares I went through in those two weeks trying to save that child," he says.
From BBC ● Jun. 28, 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
It was a series of nightmares, of dreams mixed with reality, of scenes and movements and pictures.
From "Woodsong" by Gary Paulsen
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.
