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 For instance, if a person has flashbacks and nightmares and intrusive memories, but not some other symptoms, they are not considered as having PTSD in studies. Arash Javanbakht, The Conversation, "Veterans, refugees and victims of war crimes are all vulnerable to PTSD," 21 Jan. 2020 Samuel was a nightmare for the Seahawks, scoring on a 30-yard reverse in the first half and finishing with five catches for 102 yards. Tim Booth, The Denver Post, "49ers win NFC West, No. 1 seed with Week 17 win over Seahawks," 29 Dec. 2019 Taylor 35, Humble 14: Nowlin was a nightmare for the Wildcats at NRG Stadium, recording 18 tackles (14 solo) and three TFL. Jack Marrion, Houston Chronicle, "Katy Taylor football finishes as state semifinalist," 16 Dec. 2019 Even with a spreadsheet, getting to all the beer events planned for Black Friday could be a logistical nightmare for the most organized beer lover. Kathy Flanigan, Milwaukee Journal Sentinel, "There's a free bus service to 8 Milwaukee breweries running all day on Black Friday," 25 Nov. 2019 Halloween may be over, but Billie Eilish is currently living in a real-life horror story that's probably going to give me nightmares for a week. Kelsey Stiegman, Seventeen, "Billie Eilish Says Her Mullet Was a Total Accident: "Somebody Dyed my Hair and They Burnt Half of It Off"," 6 Nov. 2019 The combination of a U.S. pullback and the escalating Turkish-Kurdish hostilities is creating a strategic nightmare for our country. Mitch Mcconnell, Twin Cities, "Mitch McConnell: Withdrawing from Syria is a grave mistake," 20 Oct. 2019 This is the question TCU fans have nightmares about. Dallas News, "3 reasons why TCU could be worse in 2020: Frogs have to replace several stars on a depleted roster," 9 Jan. 2020 But in gothic stories, dreams of the dead shade into nightmare. Fintan O’toole, The New York Review of Books, "The Designated Mourner," 7 Jan. 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

3 Feb 2020

Cite this Entry

“Nightmare.” Dictionary, Merriam-Webster, Accessed 17 Feb. 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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