onion

noun

on·​ion ˈən-yən 

plural onions

1

: a widely cultivated Asian herbaceous plant (Allium cepa) of the amaryllis family that has a pungent edible bulb and that is closely related to the garlic, chive, and leek

also : its bulb

2

: any of various usually ornamental alliums (such as Allium amplectens or A. caeruleum) related to the onion

oniony

ˈən-yə-nē 

adjective

an oniony flavor

oniony meatloaf

Examples of onion in a Sentence

The recipe calls for chopped onions.

He is growing onions in the garden this year.

The recipe calls for chopped onion.

Recent Examples on the Web

These bite-size Zucchini Chicken Enchilada Roll-ups are filled with chicken, peppers, cheese, onions and enchilada sauce. —Bethany Thayer, Freep.com, 14 Sep. 2025

The agents had been following leads from an anti-trafficking organization, the Coalition of Immokalee Workers, that in 2015 had uncovered the abuses of harvesters at an onion farm near Vidalia. —ProPublica, 13 Sep. 2025

Caramelizing the onions in the slow cooker worked fabulously. —Symiah Dorsey, Southern Living, 13 Sep. 2025

That roster includes dishes like foie gras truffle with charred onion jam and a house croissant; a wild boar belly and antelope with pistachio, fermented harissa, and yogurt; and an Asian pear sorbet with aloe sabayon and ginger tapioca. —Nicole Hoey, Robb Report, 12 Sep. 2025

Word History

Etymology

Middle English, from Anglo-French oignon, from Latin union-, unio

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing onion

• Bermuda onion
• green onion
• onion dome
• onion ring
• pearl onion
• sea onion
• Spanish onion
• spring onion

Rhymes for onion

• trunnion

Kids Definition

onion

noun

on·​ion ˈən-yən 

: a widely grown Asian herb related to the lilies and having edible bulbs that have a sharp odor and taste and are used as a vegetable and to season foods

also : its bulb