Onion (Allium cepa), herbaceous biennial plant in the amaryllis family (Amaryllidaceae), grown for its edible bulb. The onion is likely native to southwestern Asia but is now grown throughout the world, chiefly in the temperate zones. Onions are low in nutrients but are valued for their flavor and are used widely in cooking. They add flavor to such dishes as stews, roasts, soups, and salads and are also served as a cooked vegetable. Onions are among the world’s oldest cultivated plants. They were probably known in India, China, and the Middle East before recorded history. Ancient Egyptians regarded the spherical bulb as a symbol of the universe, and its name is probably derived from the Latin unus, meaning “one.” The Romans introduced the onion to Britain and, in the New World, Native Americans added a highly pungent wild onion to their stews. Curative powers have been attributed to onions throughout the centuries; they have been used in folk medicine for such varied ailments as colds, earaches, laryngitis, animal bites, burns, and warts.