Definition of "onion" []

• A bulbous plant (Allium cepa) cultivated worldwide as a vegetable. (noun)
• The rounded edible bulb of this plant, composed of fleshy, tight, concentric leaf bases having a pungent odor and taste. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The Latin for a pearl and onion is _unio_, and the pun refers to Cleopatra giving her _pearl_ (or _onion_) to Antony in a draught of wine, or, as some say, drinking it herself in toasting her lover."
• "Commonly known as nigella, this spice is also found under the name "onion seeds.""
• "Inquiring into their history, I surprisingly found the origin of the term onion dome has eluded historical record, as has the date and origin of the design."