Pronunciation: (rOO'bärb),[key] —n. 1. any of several plants belonging to the genus Rheum, of the buckwheat family, as R. officinale, having a medicinal rhizome, and R. rhabarbarum, having edible leafstalks.
2. the rhizome of any medicinal species of this plant, forming a combined cathartic and astringent.
3. the edible, fleshy leafstalks of R. rhabarbarum, used in making pies, preserves, etc.
4. Slang.a quarrel or squabble.