The onion, also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus Allium.
Its close relatives include the garlic, leek, chive, and Chinese onion.
Description of Onions, Kanda, Pyaz. … The name also describes the onion bulb when cut down the middle; it is a union of many separate, concentrically arranged layers. Onions range in size, color and taste depending upon their variety.