ETYM French ognon, from Latin unio oneness, unity, a single large pearl, an onion. Related to One, Union.
1. Bulbous plant having hollow leaves cultivated worldwide for its rounded edible bulb; SYN. onion plant, Allium cepa.
2. Edible bulb of an onion plant.
3. Pungent bulb.
Bulbous plant Allium cepa of the lily family Liliaceae. Cultivated from ancient times, it may have originated in Asia. The edible part is the bulb, containing an acrid volatile oil and having a strong flavor.
The onion is a biennial, the common variety producing a bulb in the first season and seeds in the second.