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[L. deludere, to cheat]
A fixed, false belief that is not grounded in reality and persists despite clear evidence that it is mistaken. It is seen most often in psychoses, in which patients may not be able to distinguish their own unverified thoughts, fears, or feelings from reality. It differs from hallucination in that hallucination involves the false excitation of one or more senses. The most serious delusions are those that cause patients to harm others or themselves, e.g., fear of being poisoned may cause the patient to refuse food. Delusions may lead to suicide or self-injury. False beliefs include being persecuted or being guilty of an unpardonable sin.
SEE: hallucination; SEE: illusion
delusional (di-loo′zhŏn-ăl), adj.

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