definition of
hallucination

[1] #1 hallucination n. illusory perception; a common symptom of severe mental disorder. wn

[2] #2 hallucination n. [delusion] a mistaken or unfounded opinion or idea; "he has delusions of competence"; "his dreams of vast wealth are a hallucination". wn

[3] #3 hallucination n. an object perceived during a hallucinatory episode; "he refused to believe that the angel was a hallucination". wn