any strong-smelling bulb plant of a genus (Allium) of the lily family, as the onion, garlic, leek, etc.
See allium in American Heritage Dictionary 4
(ălˈē-əm)
noun
Any of numerous, usually bulbous plants of the genus Allium in the lily family, having long stalks bearing clusters of variously colored flowers and including many ornamental and food plants, such as onions, leeks, chives, garlic, and shallots.