A nervous disorder is a condition that affects the nervous system, which can cause physical and mental symptoms. Chorea, a 6-letter term, is a type of nervous disorder characterized by involuntary, jerky movements of the arms, legs, face, and trunk. Ataxia, another 6-letter term, is a neurological sign and symptom that consists of lack of voluntary coordination of muscle movements. It can affect speech, eye movements, the ability to swallow, walking, and other motor skills.