(1):

(n.) The large and fleshy leafstalks of Rheum Rhaponticum and other species of the same genus. They are pleasantly acid, and are used in cookery. Called also pieplant.

(2):

(n.) The root of several species of Rheum, used much as a cathartic medicine.

(3):

(n.) The name of several large perennial herbs of the genus Rheum and order Polygonaceae.