rhubarb

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several plants of the genus Rheum, especially R. rhabarbarum, having long edible green or reddish leafstalks that are usually cooked and sweetened.
• noun A preparation made from the dried rhizomes and roots of any of several plants of the genus Rheum, especially R. palmatum or R. officinale of East Asia, used as a laxative.
• noun Informal A quarrel, fight, or heated discussion.

from The Century Dictionary.

• noun The general name for plants of the genus Rheum, especially for species affording the drug rhubarb and the culinary herb of that name.
• noun The root of any medicinal rhubarb, or some preparation of it.
• noun The leafstalks of the garden rhubarb collectively; pie-plant.
• Resembling rhubarb; bitter.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) The name of several large perennial herbs of the genus Rheum and order Polygonaceæ.
• noun 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.
• noun (Med.) The root of several species of Rheum, used much as a cathartic medicine.
• noun (Bot.) See under Monk.
• noun (Med.) the roots of Rheum Emodi.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any plant of the genus Rheum, especially Rheum rharbarbarum, having large leaves and long green or reddish acidic leafstalks, that are edible, in particular when cooked (although the leaves are mildly poisonous).
• noun The dried rhizome and roots of Rheum palmatum or Rheum officinale, from China, used as a laxative and purgative.
• noun A word repeated softly to emulate background conversation. (see rhubarb rhubarb).
• noun An excited, angry exchange of words, especially at a sporting event.
• noun baseball A brawl.
• noun military An RAF World War II code name for operations by aircraft (fighters and fighter bombers) seeking opportunity targets.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun plants having long green or reddish acidic leafstalks growing in basal clumps; stems (and only the stems) are edible when cooked; leaves are poisonous
• noun long pinkish sour leafstalks usually eaten cooked and sweetened