1. Any of a group of nervous disorders similar to Parkinson's disease, marked by muscular rigidity, tremor, and impaired motor control and often having a specific cause, such as the use of certain drugs or frequent exposure to toxic chemicals. Also called Parkinson's syndrome.
2. Parkinson's disease.

[From PARKINSON'S DISEASE.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.