A delusion, in everyday language, is a fixed belief that's either false, fanciful, or derived from deception. Psychiatry defines the term more specifically as a belief that's pathological (the result of an illness or illness process). As a pathology, it's distinct from a belief based on false or incomplete information, apperception, illusion, or other effects of perception. Delusions typically occur in the context of neurological or mental illness, although they are not tied to any particular… (More on Delusion)