tapioca (tăpēōˈkə) [key], widely used starchy food, obtained from the fleshy root of the bitter cassava. Tapioca is sold in flake or flour form and as the pellet pearl tapioca. Tapioca flour is widely used in place of wheat flour in regions where it is grown, e.g., South and Central America, Africa, the West Indies, and parts of India. When cooked it becomes transparent and increases in size. It is used to thicken puddings and soups.