chronic fatigue syndrome

n. A controversial disorder first described in 1988 in which a person suffers from fatigue for 6 months or more which is not alleviated by sleep and has impaired recent memory and concentration, sore throat, muscle and joint pain, and swelling and headaches. There is no known cause of chronic fatigue syndrome, although some hypothesize that it is the result of viral infection. There has been much debate as to whether this syndrome has physical or mental causes, and in recent years most physicians have moved to a belief that there are unknown physical causes.