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1. pertaining to or fulfilling a function.
2. affecting the function but not the structure.
functional disease (functional disorder) a disease or disorder of physiological function having no known organic basis. Although not strictly correct, the term is often used in psychiatry for disorders that are psychogenic and in other branches of medicine to refer to any that are idiopathic.
functional method a type of nursing care delivery system; see nursing practice.
a disorder characterized by physical symptoms with no known or detectable organic basis. See: behavior disorder, neurosis.
func·tion·al dis·or·der, functional disease (fŭngk'shŭn-ăl dis-ōr'dĕr, di-zēz')
Disease characterized by physical symptoms with no known or detectable organic basis.