Definition

1. Noun:
   • A sensory experience of something that does not exist outside the mind, often as a symptom of a mental disorder or induced by drugs or extreme fatigue: A hallucination is a perception in the absence of an external stimulus that has the compelling sense of reality.
   • A false or mistaken idea or belief; a delusion: In a more general sense, it can refer to a belief or impression that is not based in reality.

Examples

• Noun:
  • The patient reported a vivid hallucination of snakes crawling on the walls.
  • His claim that he could communicate with aliens was dismissed as a hallucination by the scientists.
  • Severe sleep deprivation can sometimes lead to auditory hallucinations.

Advanced Usage

• "to have a hallucination": to experience a hallucination.
  • Under the influence of the drug, she began to have terrifying hallucinations.
• "a hallucination of grandeur": a false belief in one's own importance, power, or identity (a specific type of delusion, often phrased as "delusions of grandeur").
  • The dictator's plans for a global empire were a hallucination of grandeur.

Variants and Related Words

• Hallucinate (verb): to experience a hallucination.
  • Some medications can cause patients to hallucinate.
• Hallucinatory (adjective): of or resembling a hallucination.
  • The fever gave him a hallucinatory vision of his childhood home.
• Hallucinogen (noun): a substance that causes hallucinations.
  • LSD is a powerful hallucinogen.

Synonyms

• Delusion: A fixed false belief, especially one resistant to reason.
• Illusion: A deceptive appearance or impression, often of something that is actually present but misinterpreted.
• Phantasm: A figment of the imagination; an illusion or apparition.
• Vision: An experience of seeing someone or something in a dream, trance, or as a supernatural apparition.

Related Phrases

• Auditory hallucination: A hallucination involving hearing sounds or voices that are not present.
  • He suffered from auditory hallucinations, hearing voices that criticized him.
• Visual hallucination: A hallucination involving seeing objects, people, or lights that are not there.
  • The visual hallucination of a loved one can be common in grief.
• Tactile hallucination: A hallucination involving the sense of touch, such as feeling insects on the skin.
  • The sensation of bugs crawling under her skin was a persistent tactile hallucination.

Related Idioms

• "Seeing things": An informal idiom meaning to have hallucinations.
  • You must be seeing things; there's no one at the door.

Noun

1. an object perceived during a hallucinatory episode
   • he refused to believe that the angel was a hallucination
2. a mistaken or unfounded opinion or idea
   • he has delusions of competence
   • his dreams of vast wealth are a hallucination
3. illusory perception; a common symptom of severe mental disorder