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

If proper guardrails aren’t put in place, AI can hallucinate wildly and give bogus information to users. —Jeremy H. Gottschalk, Forbes.com, 4 Aug. 2025

Despite rapid growth in AI use, several people are still skeptical about using AI, pointing to its penchant to hallucinate or go off the rails with strange or even offensive language. —Sydney Lake, Fortune, 25 July 2025

Some of OpenAI's most recent models hallucinate more than previous ones, TechCrunch reports. —Emily Forlini, PC Magazine, 18 June 2025

To be clear, AI still hallucinates, meaning human oversight remains crucial—especially in regulated environments like banking. —Judith Magyar, Forbes.com, 22 July 2025

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