hallucination

American  

[huh-loo-suh-nay-shuhn] / həˌlu səˈneɪ ʃən /

noun

• hallucinations
  plural

1. a sensory experience of something that does not exist outside the mind, caused by various physical and mental disorders, or by reaction to certain toxic substances, and usually manifested as visual or auditory images.

   Synonyms:

   aberration, phantasm

2. the sensation caused by a hallucinatory condition, or the object or scene visualized.

3. a false notion, belief, or impression; illusion; delusion.

4. Computers, Digital Technology. (in the field of machine learning) false information generated by a machine learning program contrary to the intent of the user and presented as if it were true and factual.

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hallucination British  

/ həˌluːsɪˈneɪʃən /

noun

1. the alleged perception of an object when no object is present, occurring under hypnosis, in some mental disorders, etc

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hallucination Cultural  

1. A false perception that appears to be real, as when, for example, a man dying of thirst in a desert thinks that he sees a lake. (See also delusion.)

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Usage

What is a hallucination? A hallucination is a sensory experience of something that does not actually exist and has no basis in reality. Hallucinations can be caused by mental disorders or toxic substances. A hallucination often takes the form of visual images or noises, as in Sangeet saw a hallucination of sparkling lights. Hallucination can also be used to refer to the sensation caused by one of these false sensory experiences, as in Roman was suffering from drug-induced hallucinations. More generally, hallucination can be used to mean a false notion or belief, as in His idea of what life was like in Canada was nothing more than a silly hallucination. Hallucination is similar to the words illusion and delusion, which also describe false beliefs or experiences. An illusion is a false image that is a result of a distortion or manipulation of actual things. For example, makeup can create the illusion that a person is younger than they actually are. A delusion is a persistent, false belief that may or may not be partially based on reality, as in The athlete’s huge ego constantly made him have delusions of being unbeatable. Example: The explorer suffered from terrifying hallucinations of ghosts and phantoms after eating the toxic mushrooms.

Synonym Usage

See illusion.

Other Word Forms

Derived Forms

• nonhallucination
  noun
• hallucinational
  adjective
• hallucinative
  adjective

Inflected Forms

Nouns

• hallucinations
  plural

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Etymology

Origin of hallucination

First recorded in 1640–50; from Latin hallūcinātiōn-, stem of hallūcinātiō, variant of (h)ālūcinātiō, “a wandering of the mind”; hallucinate + -ion

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Explanation

If you see your teacher morph into a dancing elephant, chances are you’re having a hallucination, or an illusory perception. In other words, it sounds like you are seeing things! A person experiencing a hallucination perceives things that aren’t really there. A hallucination can involve any of the senses — including sight, hearing, touch, smell, and taste — and often results from a mental disorder or a chemical source, such as a drug.

Example Sentences

See Examples For:

hallucination hallucinations

If reality truly is nothing more than a hallucination, dream or computer screensaver in the brain, why should we waste time disputing it?

From Salon ● Oct. 15, 2026

"For a young person, if you don't have what we call 'foundational knowledge' it might be hard for you to figure out whether something is a hallucination or whether it's genuine."

From BBC ● Oct. 5, 2026

Modifying weights can make a model more polite, sassier or more prone to hallucination.

From The Wall Street Journal ● Aug. 11, 2026

An episode is prison slang for a severe hallucination.

From Slate ● Aug. 11, 2026

I know looking back on it that it was a hallucination.

From "Woodsong" by Gary Paulsen

According to the NHS, the condition affects about one in 1,000 new mothers and can include symptoms such as hallucinations, paranoia and depression.

From BBC ● Nov. 6, 2026

We still can’t trust the output of artificial-intelligence models because of hallucinations.

From The Wall Street Journal ● Nov. 1, 2026

The mystery resurfaced during the 1990s, when people in Yunnan, Southwest China, reported similar hallucinations after eating bolete mushrooms.

From Science Daily ● Oct. 25, 2026

Laycock also teaches pupils about "hallucinations" where AI confidently provides information it has made up.

From BBC ● Oct. 5, 2026

“A good joke. Where was I? Secondary hallucinations, yes. Women come to me with snakes crawling from their ears. When I cure them, the snakes vanish.”

From "The Martian Chronicles" by Ray Bradbury

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Related Words

• illusion
• phantom

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