hallucination

noun

hal·​lu·​ci·​na·​tion hə-ˌlü-sə-ˈnā-shən How to pronounce hallucination (audio)
plural hallucinations
1
a
: a sensory perception (such as a visual image or a sound) that occurs in the absence of an actual external stimulus and usually arises from neurological disturbance (such as that associated with delirium tremens, schizophrenia, Parkinson's disease, or narcolepsy) or in response to drugs (such as LSD or phencyclidine)
visual/auditory/olfactory/gustatory/tactile hallucinations
a drug-induced hallucination
An important aspect of the study of hallucinations is the judgement of reality. How does a patient confer the character of reality on stimuli which, beyond any reasonable doubt, originate in his own mind?Cesare Davalli et al.
b
: the object of a hallucinatory perception
wasn't sure if the creature was real or a hallucination
2
: an unfounded or mistaken impression or notion : delusion
… that popular hallucination, from which not even great scientists are … free …Lewis Mumford
3
computing : a plausible but false or misleading response generated by an artificial intelligence algorithm
"This type of artificial intelligence we're talking about can sometimes lead to something we call hallucination," said Prabhakar Raghavan in an interview with Germany's Welt am Sonntag newspaper published on Saturday. "This is then expressed in such a way that a machine delivers a convincing but completely fictitious answer."Matthew Broersma
Choose the Right Synonym for hallucination

delusion, illusion, hallucination, mirage mean something that is believed to be true or real but that is actually false or unreal.

delusion implies an inability to distinguish between what is real and what only seems to be real, often as the result of a disordered state of mind.

delusions of persecution

illusion implies a false ascribing of reality based on what one sees or imagines.

an illusion of safety

hallucination implies impressions that are the product of disordered senses, as because of mental illness or drugs.

suffered from terrifying hallucinations

mirage in its extended sense applies to an illusory vision, dream, hope, or aim.

claimed a balanced budget is a mirage

Examples of hallucination in a Sentence

He could not tell if what he was seeing was real or if it was a hallucination. He has been having hallucinations due to the medication.
Recent Examples on the Web Irrelevant and outdated information could cause hallucinations and undesirable behavior. Gregorio Alejandro Patiño Zabala, Forbes, 4 Oct. 2024 As with psilocybin, consuming components of Amanita muscaria can lead to psychedelic effects including hallucinations and altered perceptions of sight, sound, time, and space. Jamie Ducharme, TIME, 4 Oct. 2024 The Third Realm puts us instead in Tove’s head, a blast furnace of creative fury and intrusive hallucinations that compete with her family for her attention. Lev Grossman, The Atlantic, 30 Sep. 2024 Edibles consumed in larger doses can also cause mild hallucinations and paranoia. Tribune Content Agency, The Mercury News, 30 Sep. 2024 See all Example Sentences for hallucination 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'hallucination.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

see hallucinate

First Known Use

1629, in the meaning defined at sense 1a

Time Traveler
The first known use of hallucination was in 1629

Dictionary Entries Near hallucination

Cite this Entry

“Hallucination.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hallucination. Accessed 16 Oct. 2024.

Kids Definition

hallucination

noun
hal·​lu·​ci·​na·​tion hə-ˌlüs-ə-ˈnā-shən How to pronounce hallucination (audio)
: the awareness of something (as a visual image, a sound, or a smell) that seems to be experienced through one of the senses but is not real, cannot be sensed by someone else, and is usually the result of mental illness or the effect of a drug
also : something of which one is aware but which is not real

Medical Definition

hallucination

noun
hal·​lu·​ci·​na·​tion hə-ˌlüs-ᵊn-ˈā-shən How to pronounce hallucination (audio)
1
: a sensory perception (as a visual image or a sound) that occurs in the absence of an actual external stimulus and usually arises from neurological disturbance (as that associated with delirium tremens, Lewy body disease, schizophrenia, Parkinson's disease, or narcolepsy) or in response to drugs (as LSD or phencyclidine)
visual/auditory/olfactory/gustatory/tactile hallucinations
a drug-induced hallucination
compare delusion sense 2, illusion sense 2a
2
: the object of a hallucinatory perception
Last Updated: - Updated example sentences
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