rhubarb Definition

any of a genus (Rheum) of Asian plants of the buckwheat family having large leaves with thick petioles often used as food; also : the petioles of rhubarb

the tart, succulent, usually pink or red petioles of rhubarb used especially in pies and preserves

the dried rhizome and roots of any of various rhubarbs (such as Rheum officinale and R. palmatum) grown chiefly in temperate parts of China and used in folk medicine especially as a laxative, diuretic, and ulcer treatment