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Any of a group of toxic alkaloids, including atropine and scopolamine, found in plants such as belladonna and jimsonweed. These alkaloids are used in medicine in low doses to dilate the pupils of the eyes, dry respiratory passages, prevent motion sickness, and relieve cramping of the intestines and bladder.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.