night·​mare | \ ˈnīt-ˌmer How to pronounce nightmare (audio) \

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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Other Words from nightmare

nightmare adjective
nightmarish \ ˈnīt-​ˌmer-​ish How to pronounce nightmarish (audio) \ adjective
nightmarishly adverb

Synonyms & Antonyms for nightmare



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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.

Examples of nightmare in a Sentence

Mommy, I had a really scary nightmare. The party was a complete nightmare.
Recent Examples on the Web The scene outside a county conference room in early September was a pandemic nightmare. Antonio Olivo, Washington Post, "Virginia suburb once known for Corey Stewart gets a new provocateur: A Latina Republican," 17 Oct. 2020 Yet while last year’s Notre Dame game created confidence that U of L was again competitive following its nightmare 2018 season — the game was still tied until the final minute of the first half — this one has a feel of foreboding. Tim Sullivan, The Courier-Journal, "With Notre Dame next, U of L's Satterfield sounds resigned to long rebuild," 15 Oct. 2020 The event was becoming an organizationally nightmare, the prizes too lavish, corporate intrusions too frustrating. Rick Kogan,, "Column: Did Mike Royko make the greatest ribs Chicago has ever known? No. But he did make the greatest Ribfest.," 14 Oct. 2020 Soccer’s world governing body had already flagged this international break as a potential logistical nightmare. Joshua Robinson, WSJ, "Covid-19, Cristiano Ronaldo, and the Risks of International Soccer," 14 Oct. 2020 Cornerback Cameron Dantzler had a nightmare ending in what was shaping up to be a strong game for the Vikings’ young and vulnerable defense in Seattle. Andrew Krammer, Star Tribune, "Film review: Vikings' calls, secondary held down Russell Wilson, until they didn't," 13 Oct. 2020 Alabama’s 63-48 win over Ole Miss was a defensive coach’s nightmare and Nick Saban built his reputation on that side of the ball. Michael Casagrande |, al, "Nick Saban was ‘boiling and bubbling’ on sideline as Alabama defense struggled," 11 Oct. 2020 The kids look concerned, but manage to keep Dani occupied with a story about their mom showing up in Flora’s nightmare. Shannon Carlin,, "The Haunting of Bly Manor," 9 Oct. 2020 Customer service is the five-syllables nightmare just about everyone has dealt with—especially during the pandemic. Lucinda Shen, Fortune, "MessageBird becomes a unicorn thrice over," 8 Oct. 2020

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.

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First Known Use of nightmare

14th century, in the meaning defined at sense 1

History and Etymology for nightmare

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

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Time Traveler for nightmare

Time Traveler

The first known use of nightmare was in the 14th century

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Statistics for nightmare

Last Updated

20 Oct 2020

Cite this Entry

“Nightmare.” Dictionary, Merriam-Webster, Accessed 30 Oct. 2020.

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More Definitions for nightmare


How to pronounce nightmare (audio)

English Language Learners Definition of nightmare

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


night·​mare | \ ˈnīt-ˌmer How to pronounce nightmare (audio) \

Kids Definition of nightmare

1 : a frightening dream
2 : a horrible experience

Other Words from nightmare

nightmarish \ ˈnīt-​ˌmer-​ish \ adjective


night·​mare | \ ˈnīt-ˌma(ə)r, -ˌme(ə)r How to pronounce nightmare (audio) \

Medical Definition of nightmare

: a frightening or distressing dream that usually awakens the sleeper

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