nightmare

noun night·mare \ ˈnīt-ˌmer \

|Updated on: 9 Jun 2018

Definition of nightmare

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

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nightmare

adjective

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nightmarish

play \ˈnīt-ˌmer-ish\ adjective

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nightmarishly

adverb

See nightmare defined for English-language learners

See nightmare defined for kids

nightmare was our Word of the Day on 03/24/2017. Hear the podcast!

Examples of nightmare in a Sentence

Mommy, I had a really scary nightmare.
The party was a complete nightmare.

Recent Examples of nightmare from the Web

Finally, the Department of Transportation may be bringing our long emotional support animal nightmare to an end.

— wes siler, Outside Online, "You May Never Fly with Your Fake Service Dog Again," 30 May 2018
Better Angels was launched in 2016 with the aim of awakening America’s citizenry from its partisan nightmare.

— The Economist, "The primeval tribalism of American politics," 24 May 2018
In your worst nightmares, how does your flirting go wrong?

— hannah orenstein, Seventeen, "What Kind of Flirt Are You?," 21 May 2018
Hal was just a kid at the time, but his mother (who sounds like a true nightmare) forced him to convince a young Svenson not to reveal the truth about who killed the Conways.

— refinery29.com, "Riverdale Just Confirmed Your Favorite Black Hood Theory, But There's A Big Twist," 10 May 2018
This is especially significant given the moment Arnold tells Dolores about his water-themed nightmare at the beginning of the episode.

— mehera bonner, Harper's BAZAAR, "A Genius New Westworld Theory Says There Are Multiple Bernards This Season," 23 Apr. 2018
The American Dream can sometimes feel like a nightmare.

— kat bein, Billboard, "Logic & Marshmello Re-Enact 'Office Space' in 10-Minute 'Everyday' Music Video: Watch," 17 Apr. 2018
The combination of all the testosterone and alcohol starts to get out of hand, and Tyler’s precarious situation starts to feel like a nightmare.

— mia galuppo, The Hollywood Reporter, "Magnolia Pictures Picks Up Jason Mitchell Drama 'Tyrel'," 17 Apr. 2018
Even in his worst nightmare, Tom Mauser would never have dreamed what happened on April 20, 1999, at Columbine High School in Littleton, Colorado.

— scott mclean and rachel clarke, CNN, "A dreamcatcher's journey reveals hope, change and frustration after 19 years of school shootings," 23 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'nightmare.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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 a 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.

Origin and Etymology of nightmare

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

NEW! Time Traveler

First Known Use: 14th century

in the meaning defined at sense 1

See Words from the same year

nightmare Synonyms

NIGHTMARE Defined for English Language Learners

nightmare

noun

Definition of nightmare for English Language Learners

: a dream that frightens a sleeping person : a very bad dream
: a very bad or frightening experience or situation

NIGHTMARE Defined for Kids

nightmare

noun night·mare \ ˈnīt-ˌmer \

Definition of nightmare for Students

1 : a frightening dream

2 : a horrible experience

—

nightmarish

\ˈnīt-ˌmer-ish\ adjective

History for nightmare

The -mare in nightmare comes from an Old English word for a kind of evil spirit. Such spirits were believed to bother people who were sleeping.

Medical Dictionary

nightmare

noun night·mare \ ˈnīt-ˌma(ə)r, -ˌme(ə)r \

medical Definition of nightmare

: a frightening or distressing dream that usually awakens the sleeper

Learn More about nightmare

See words that rhyme with nightmare Thesaurus: All synonyms and antonyms for nightmare Spanish Central: Translation of nightmare Nglish: Translation of nightmare for Spanish speakers Britannica English: Translation of nightmare for Arabic speakers Britannica.com: Encyclopedia article about nightmare

Seen and Heard

What made you want to look up nightmare? Please tell us where you read or heard it (including the quote, if possible).

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nightmare

Definition of nightmare

nightmare

nightmarish

nightmarishly

nightmare was our Word of the Day on 03/24/2017. Hear the podcast!

Examples of nightmare in a Sentence

Recent Examples of nightmare from the Web

Did You Know?

Origin and Etymology of nightmare

nightmare Synonyms

Synonyms

Antonyms

Near Antonyms

Related Words

Phrases Related to NIGHTMARE

Related Phrases

NIGHTMARE Defined for English Language Learners

nightmare

Definition of nightmare for English Language Learners

NIGHTMARE Defined for Kids

nightmare

Definition of nightmare for Students

nightmarish

History for nightmare

Medical Dictionary

nightmare

medical Definition of nightmare

Learn More about nightmare

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