Real Dictionary

rhubarb
uncountable noun: Rhubarb is a plant with large leaves and long red stems. You can cook the stems with sugar to make jam or puddings.

rhubarb in American English
any of a genus (Rheum) of perennial, large-leaved plants of the buckwheat family; esp., the domestic pieplant (R. rhaponticum), having large, cordate leaf blades borne on long, thick stalks: the stalks are cooked into a sauce or baked in pies, but the bla
noun: 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

rhubarb in British English
noun: any of several temperate and subtropical plants of the polygonaceous genus Rheum, esp R. rhaponticum (common garden rhubarb), which has long green and red acid-tasting edible leafstalks, usually eaten sweetened and cooked
verb: to simulate conversation, esp by repeating the word rhubarb at random