from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Perception of visual, auditory, tactile, olfactory, or gustatory experiences without an external stimulus and with a compelling sense of their reality, usually resulting from a mental disorder or as a response to a drug.
  • noun The objects or events so perceived.
  • noun A false or mistaken idea.

from The Century Dictionary.

  • noun An unfounded notion; belief in an unreality; a baseless or distorted conception.
  • noun In pathology and psychology, the apparent perception of some external thing to which no real object corresponds.
  • noun Synonyms Delusion, Illusion (see delusion); phantasm.

from the GNU version of the Collaborative International Dictionary of English.

  • noun The act of hallucinating; a wandering of the mind; error; mistake; a blunder.
  • noun (Med.) The perception of objects which have no reality, or of sensations which have no corresponding external cause, arising from disorder of the nervous system, as in delirium tremens; delusion.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A sensory perception of something that does not exist, arising from disorder of the nervous system, as in delirium tremens; a delusion.
  • noun The act of hallucinating; a wandering of the mind; an error, mistake or blunder.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun an object perceived during a hallucinatory episode
  • noun illusory perception; a common symptom of severe mental disorder
  • noun a mistaken or unfounded opinion or idea


from Wiktionary, Creative Commons Attribution/Share-Alike License

Derives from verb to hallucinate, from Latin hallucinatus. Compare French hallucination. The first known usage in the English language is from Sir Thomas Browne.


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  • We then see a Yin hallucination (a tearful Yin says “Sayonara, Hei” while he tries to grab her).

    Darker than Black season 2 – ep 02 « Undercover 2009

  • I fell prey to water intoxication or low sodium, which is characterized by hallucination, memory loss, and corporal ineptness; a veritable cornucopia of psychoses.

    In the Fullness of Time Emily W. Upham 2010

  • The only hallucination is that republican values are good for america – and you seem to be quite high …

    Think Progress » Bush: “It’s Gonna Cost Whatever It Costs” 2005

  • The other partisans of a natural explanation while avoiding the word hallucination, eventually fall back on the system of Renan which they merely endeavour to render a little less complicated.

    The Catholic Encyclopedia, Volume 11: New Mexico-Philip 1840-1916 1913

  • It was an elaborate hallucination, which is why he'll open the season in a rehab institution.

    Critic's Corner Monday 2009

  • Unlike a hallucination, which is a sensory experience in the absence of a stimulus, an illusion describes a misinterpretation of a true sensation so it is perceived in a distorted manner.

    Carry-Over Thread 2007

  • There are genuine moments of art floating about in the movie - namely a hallucination sequence as well as an exhausting escape by sea that really are heightened by the animation - but there are images in here that are not done justice by Folman's decision to make the film the way that he has.

    Archive 2009-05-01 Glenn Dunks 2009

  • I was AGAIN woken from my nap by a pain hallucination, which is a BAD sign since I woke yesterday by the screaming moan I was giving off, waking me and Linda both; which indicates that my body is in BAD pain.

    Archive 2008-06-01 Elizabeth McClung 2008

  • I was AGAIN woken from my nap by a pain hallucination, which is a BAD sign since I woke yesterday by the screaming moan I was giving off, waking me and Linda both; which indicates that my body is in BAD pain.

    Don’t go into the woods today….it’s the Dyke’s picnic! Elizabeth McClung 2008

  • The pack needs a catalyst to allow their shape to shift and in this book the part is taken by the Amarita mushroom usually known as a hallucination inducing drug.

    Archive 2008-04-01 2008

  • This would reduce the gargantuan amount of data necessary to train systems such as ChatGPT and would minimize ‘hallucination’, which occurs when AI perceives patterns that are non-existent and creates inaccurate outputs.

    AI ‘breakthrough’: neural net has human-like ability to generalize language Max Kozlov 2023


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  • "Any man who was supported by a kapok jacket was in bad shape. The life jackets had offered a wonderful sense of security for the first twenty-four hours, but they were designed to keep one afloat for a maximum of forty-eight hours, and now with the time almost doubled, they afforded hardly enough buoyancy to keep a man's chin out of the water.

    "Little Ernest McKenzie, with all of his five feet four inches, was still holding on to life fairly well. From the first night he and his buddy, Tommy Lockwood, had formed a team. They tied themselves together at night and took turns sleeping while the other stayed on watch. The system had faltered badly on Wednesday night, however, and McKenzie drifted off by himself. He thought he had been picked up by an English ship and taken to port. One of the British sailors told him that he was free to go on liberty but explained that he would have to wear the pneumatic tube all of the time he was on shore.

    "Never one to take orders seriously, McKenzie agreed to the stipulation but as soon as he was ashore he slipped around behind a building and removed the life belt that had already begun to rub his chest raw. Suddenly the dream was over and McKenzie, who had survived the sinking of the Bismarck Sea,, snapped back to reality. He was off by himself and in his delirium he had removed his belt and was managing to stay afloat only by swimming. Somewhere, it seemed a long way off, he could hear men talking and he began swimming in that direction. When he reached the group, he fortunately found an empty kapok jacket and in a little while he located his buddy, Tommy Lockwood.

    "'What the hell did you leave me for?' Lockwood demanded. 'I had over a hundred cases of cold beer.'

    "'Beer?' McKenzie said. 'Where the hell did you get any beer?'

    "'Never mind where I got it,' Lockwood said. 'If you hadn't gone running off, you could have handed it out while I collected the money. But damn you, the guys rushed me and took it away from me and I didn't get a damn dime.'"

    —Thomas Helm, Ordeal by Sea: The Tragedy of the U.S.S. Indianapolis, 1963 (New York: Signet, 2001), 154

    November 14, 2008

  • Yikes. That sounds like one scary story.

    November 14, 2008

  • I thought the situation was terrifying, of course, but this story just made me smile to hear the guys both talking as if their dream worlds were real...

    November 15, 2008

  • Yes, it's pretty funny. I like that kind of humor, but I was overwhelmed by the horror of the whole situation.

    November 15, 2008

  • Yes, I thought about this some more. I think by this point in the book you're ... not inured, that isn't the right word... but there's so much horror, when these guys lost their minds it often had violent and tragic results. I was amused at this story in contrast to those more violent anecdotes, but also kind of stunned by how specific and ordinary these guys' dreams were, and how the human brain works.

    November 15, 2008

  • Good point. Maybe that's what makes it so horrific--the fact that they were having what seemed like goofy old run-of-the-mill dreams in such an awful situation.

    November 15, 2008