chronic fatigue syndrome (CFS), a condition characterized by disabling fatigue, accompanied by a constellation of symptoms, including muscle pain, multijoint pain without swelling, painful cervical or axillary adenopathy, sore throat, headache, impaired memory or concentration, unrefreshing sleep, and postexertional malaise. This diagnosis requires that a patient have four or more symptoms concurrently that persist for 6 or more months. The diagnosis is one of exclusion. Also called immune dysfunction syndrome.
