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an obsolete term once used to denote schizophrenia and other severe mental disorders before modern science discovered a biological component to some aspects of each of the disorders.
func·tion·al psy·cho·sis(fungkshŭn-ăl sī-kōsis)
Mental disorder that does not have a verifiable physical cause.
A psychosis in which there is no apparent pathology of the central nervous system.
See also: psychosis