noun (n)

• the bulb of an onion plant(noun.plant)

  source: wordnet30
• bulbous plant having hollow leaves cultivated worldwide for its rounded edible bulb(noun.plant)

  Synonym:
  allium cepa, onion plant
  

  source: wordnet30
• an aromatic flavorful vegetable(noun.food)

  source: wordnet30
• A liliaceous plant of the genus Allium (A. cepa), having a strong-flavored bulb and long hollow leaves; also, its bulbous root, much used as an article of food. The name is often extended to other species of the genus.(noun)

  source: webster1913