English Reference
Noun

hallucination

n.
C1 Advanced US /həˌɫusəˈneɪʃən/ UK /hɐlˌuːsɪnˈeɪʃən/ hal·lu·ci·na·tion UK spelling hallucinations

n.a feeling or image that you see, hear, or feel in your mind when there is nothing there. It is like seeing or hearing something that is not real.

n.a sensory perception that occurs without any external stimulus. It is often used to describe a mental state where a person experiences sights, sounds, or sensations that are not present in reality.


SIMPLE

He had a hallucination of hearing his mother's voice.

CONTEXTUAL

The patient reported a vivid hallucination of a bright light in the room, though no one else saw it.

COMPLEX

In the final stages of the illness, the patient experienced complex hallucinations that blurred the line between memory and reality, making it difficult for caregivers to provide consistent support.

Chatbots can make mistakes or entirely make things up – called “hallucinations” in the AI field – while showing great confidence in these inaccuracies.

The Conversation· 13 Aug 2026

So far so polemical, but the appeal of Kushner’s play is the way it blurs into the mythic with its feverish hallucinations.

The Guardian· 16 Aug 2026

Common in culture and technology writing


Derives from the verb hallucinate, from Latin hallucinatus. Compare French hallucination. The first known usage in the English language is from Sir Thomas Browne.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C1 · Advanced
Frequency Occasional
Updated