Dictionary.net

Disorders in which the symptoms are distressing to the individual and recognized by him or her as being unacceptable. Social relationships may be greatly affected but usually remain within acceptable limits. The disturbance is relatively enduring or recurrent without treatment.

A generic name for diseases supposed to have their seat in the nervous system, and which are indicated by disordered sensation, volition, or mental manifestation; without any evident lesion in the structure of the parts, and without any material agent producing them. Such is the usual definition. Broussais attributes them to a state of irritation of the brain and spinal marrow.