a progressive disease of the nervous system marked by tremor, muscular rigidity, and slow, imprecise movement, chiefly affecting middle-aged and elderly people. It is associated with degeneration of the basal ganglia of the brain and a deficiency of the neurotransmitter dopamine.
late 19th century: named after James Parkinson (1755–1824), English surgeon
Parkinson's disease in other Oxford dictionaries
Definition of Parkinson's disease in the US English dictionary