hallucination

[huh-loo-suh-ney-shuhn]

noun

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.

hallucination

/ həˌluːsɪˈneɪʃən /

noun

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

hallucination

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.)

Other Word Forms

• hallucinational adjective
• hallucinative adjective
• nonhallucination noun

Word History and Origins

Origin of hallucination¹

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

Synonym Study

See illusion.

Example Sentences

This AI hallucination problem remains a significant obstacle to fully autonomous cyberattacks—at least for now.

Read more on The Wall Street Journal

Such AI hallucinations remain a persistent concern across the technology.

Read more on Barron's

The automated hacks weren’t capable of being fully autonomous, with so-called AI hallucinations leading to mistakes.

Read more on The Wall Street Journal

Schizophrenia is a serious mental health disorder that typically begins in early adulthood and is often marked by hallucinations, delusions, and disorganized thinking.

Read more on Science Daily

While we are largely familiar now with the "hallucinations" of generative AI tools, quantum is plagued by a different kind of error.

Read more on BBC

Related Words

• illusion 
• phantom 

When To Use

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.