Wordnet 3.0
NOUN (1)
1.
any of various plants of the genus Allium with edible bulbs found growing wild;
The Collaborative International Dictionary of English v.0.48:
Onion \On"ion\, n. [F. ognon, fr. L. unio oneness, unity, a
single large pearl, an onion. See One, Union.]
1. (Bot.) A liliaceous plant of the genus Allium (Allium
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.
[1913 Webster]
2. The flavor of an onion[1].
[PJC]
Onion fish (Zool.), the grenadier.
Onion fly (Zool.) a dipterous insect whose larva feeds upon
the onion; especially, Anthomyia ceparum and Ortalis
flexa.
Welsh onion. (Bot.) See Cibol.
Wild onion (Bot.), a name given to several species of the
genus Allium.
[1913 Webster]
WordNet (r) 3.0 (2006):
wild onion
n 1: any of various plants of the genus Allium with edible bulbs
found growing wild