On"ion (?), n. [F. ognon, fr. L.
unio oneness, unity, a single large pearl, an onion. See
One, Union.] (Bot.) 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.
Onion fish (Zoöl.), the
grenadier. -- Onion fly (Zoöl.)
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.