a terrifying dream in which the dreamer experiences feelings of helplessness, extreme anxiety, sorrow, etc.
a condition, thought, or experience suggestive of a nightmare: the nightmare of his years in prison.
(formerly) a monster or evil spirit believed to oppress persons during sleep.

Origin of nightmare

Middle English word dating back to 1250–1300; see origin at night, mare2

Synonyms for nightmare

Synonym study

1. See dream. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for nightmare

Contemporary Examples of nightmare

Historical Examples of nightmare

  • The dread of French domination seems to have haunted him like a nightmare.

    Biographical Sketches

    Nathaniel Hawthorne

  • The dread of poverty is a nightmare; it wears one's life threadbare.


    W. A. Fraser

  • What was it—madness, a nightmare, or a trap into which he had been decoyed with fiendish artfulness?

    The Secret Agent

    Joseph Conrad

  • For there is nothing so delightful as a nightmare—when you know it is a nightmare.

    Alarms and Discursions

    G. K. Chesterton

  • So a nightmare of thought teemed through his brain as he rode.

    The Law-Breakers

    Ridgwell Cullum

British Dictionary definitions for nightmare



a terrifying or deeply distressing dream
  1. an event or condition resembling a terrifying dreamthe nightmare of shipwreck
  2. (as modifier)a nightmare drive
a thing that is feared
(formerly) an evil spirit supposed to harass or suffocate sleeping people
Derived Formsnightmarish, adjectivenightmarishly, adverbnightmarishness, noun

Word Origin for nightmare

C13 (meaning: incubus; C16: bad dream): from night + Old English mare, mære evil spirit, from Germanic; compare Old Norse mara incubus, Polish zmora, French cauchemar nightmare
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for nightmare

late 13c., "an evil female spirit afflicting sleepers with a feeling of suffocation," compounded from night + mare (3) "goblin that causes nightmares, incubus." Meaning shifted mid-16c. from the incubus to the suffocating sensation it causes. Sense of "any bad dream" first recorded 1829; that of "very distressing experience" is from 1831. Cognate with Middle Dutch nachtmare, German Nachtmahr.

Online Etymology Dictionary, © 2010 Douglas Harper

nightmare in Medicine




A dream arousing feelings of intense fear, horror, and distress.
An event or experience that is intensely distressing.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.