APA Dictionary of Psychology

n. a syndrome of uncertain origin that is characterized by widespread musculoskeletal pain and chronic fatigue. Pain may be triggered by pressure on numerous tender points on the body. Other commonly associated symptoms are muscle stiffness, headaches, sleep disturbance, and depression. Symptoms overlap with those of chronic fatigue syndrome, and fibromyalgia often occurs simultaneously with other disorders, such as irritable bowel syndrome and migraine. The condition was formerly called fibromyositis–fibromyalgia syndrome. See also chronic myofascial pain.