1. Illusory perception; a common symptom of severe mental disorder
   "The patient reported visual hallucinations of shadowy figures"
    
2. A mistaken or unfounded opinion or idea
   "his dreams of vast wealth are a hallucination";
   - delusion
    
3. An object perceived during a hallucinatory episode
   "he refused to believe that the angel was a hallucination"
    
4. An incorrect or invented response given by an artificial intelligence system
   "The AI's hallucination about historical events confused the users"

Derived forms: hallucinations

Type of: delusion, misconception, object, psychotic belief

Encyclopedia: Hallucination