In standard psychiatric terms, a functional
disorder in which the symptoms of delusions of jealousy and delusions of either
grandeur and/or persecution cannot be explained by other disorders, such as
schizophrenia, organic mental disorder, or organic brain syndrome. In the
classic form, the delusions develop insidiously and become knit together into a
rational and coherent set of beliefs that is internally consistent and, once the
initial set of assumptions is accepted, compelling and vigorously defensible. In
paranoia, intellectual functioning is otherwise unimpaired and the paranoid is
quite capable of coherent behavior within the delusional system.