[ nahyt-mair ]
/ ˈnaɪtˌmɛər /


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.

Nearby words

  1. nightingale, florence,
  2. nightjar,
  3. nightlife,
  4. nightlong,
  5. nightly,
  6. nightmarish,
  7. nightrider,
  8. nights,
  9. nightscape,
  10. nightshade

Origin of nightmare

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

Synonym study

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

Examples from the Web for nightmare

British Dictionary definitions for nightmare


/ (ˈnaɪtˌmɛə) /


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

Medicine definitions for nightmare


[ nītmâr′ ]


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.