Hallucinations are
Hallucination A hallucination is a perception experienced in the absence of an external stimulus. The hallucinations can be in the auditory, visual, olfactory, gustatory or tactile domains. Auditory hallucinations are commonest types of hallucinations in non-organic psychiatric disorders. Ref: A Sho Textbook of Psychiatry, Niraj Ahuja, 7th Edition, pg. no. 13
Feeling of familiarity with unfamiliar thing
Alteration of perception of one reality
Misinterpretation of stimuli
Perception occurring without external stimulation
Symptoms and signs in psychiatry and classification