hallucination

UK: /həˌluːsɪˈneɪʃ^ən/

US: /həˌlusəˈneɪʃən/

US: (hə lo̅o̅′sə nā′shən)

WordReference Random House Learner's Dictionary of American English © 2026

hal•lu•ci•na•tion /həˌlusəˈneɪʃən/   n. [countable]

1. Psychiatry perception of something that does not exist, caused by various diseases, or by reaction to toxic substances or drugs:
   This drug causes bizarre hallucinations.

hal•lu•ci•na•to•ry /həˈlusənəˌtɔri/  adj. 

WordReference Random House Unabridged Dictionary of American English © 2026

hal•lu•ci•na•tion  (hə lo̅o̅′sə nā′shən), n. 

1. Psychiatry 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.
2. Psychiatry the sensation caused by a hallucinatory condition or the object or scene visualized.
3. a false notion, belief, or impression; illusion;
   delusion.

• Latin hallūcinātiōn- (stem of (h)allūcinātiō) a wandering of the mind. See hallucinate, -ion
• 1640–50

hal•lu′ci•na′tion•al, hal•lu•ci•na•tive  (hə lo̅o̅′sə nā′tiv, -nə tiv), adj.  Synonyms

• 1. phantasm, aberration. See illusion. 

Collins Concise English Dictionary © HarperCollins Publishers::

hallucination / həˌluːsɪˈneɪʃən/ noun

1. the alleged perception of an object when no object is present

halˌluciˈnational, halˈlucinative, halˈlucinatory adjective