hallucinate

verb

hal·​lu·​ci·​nate hə-ˈlü-sə-ˌnāt 

hallucinated; hallucinating

transitive verb

1

: to affect with visions or imaginary perceptions

2

: to perceive or experience as a hallucination

intransitive verb

: to have hallucinations

hallucinator

hə-ˈlü-sə-ˌnā-tər 

noun

Examples of hallucinate in a Sentence

The patient may hallucinate if she has a fever.

Recent Examples on the Web

Without a way to connect identity and meaning across platforms, agents hallucinate, miss signals or produce outputs that look plausible but are wrong. — Michel Tricot, Forbes.com, 31 July 2026

Despite certain improvements in accuracy, large language models still hallucinate a lot. — Joe Wilkins, Futurism, 29 July 2026

Meanwhile, software platforms could identify frequently hallucinated names before attackers register them. — Kurt Knutsson, FOXNews.com, 18 July 2026

When a developer, for instance, instructs a coding agent to clone a popular new repository, the LLM hallucinates its correct location up to 85 percent of the time. — Dan Goodin, ArsTechnica, 8 July 2026

Word History

Etymology

Latin hallucinatus, past participle of hallucinari, allucinari to prate, dream, modification of Greek alyein to be distressed, to wander

First Known Use

circa 1834, in the meaning defined at transitive sense 1

Kids Definition

hallucinate

verb

hal·​lu·​ci·​nate hə-ˈlüs-ə-ˌnāt 

hallucinated; hallucinating

: to have hallucinations or experience as a hallucination

Medical Definition

hallucinate

verb

hal·​lu·​ci·​nate hə-ˈlüs-ᵊn-ˌāt 

hallucinated; hallucinating

transitive verb

1

: to affect with visions or imaginary perceptions

the patient is not hallucinated

2

: to perceive or experience as a hallucination

may hallucinate monsters or attackers

—M. J. Horowitz

intransitive verb

: to have hallucinations