rhubarb

noun

1. 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 blades are poisonous
2. the roots and rhizomes of various Asiatic rhubarbs, used as a cathartic
3. ☆ Slang a heated discussion or argument