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

Tomatoes, roux and the Holy Trinity of diced onions, celery and green bell peppers are the foundation for many a Creole dish. — Catherine Garcia, TheWeek, 20 July 2026

Edward’s new Adana filet saute is reminiscent of Iraqi beef chillifry and Turkish et sote, with strips of filet mignon sautéed with onions, tomatoes, pepper paste and a touch of Persian curry powder. — Jenn Harris, Los Angeles Times, 20 July 2026

Fresh yerba mate; Paraguayan sopa, a moist, dense cornbread made with cheese and onions; and vori vori, a rich chicken-and-dumpling soup, are among the highlights. — Kate Bradshaw, Mercury News, 20 July 2026

Also, take care to keep potatoes away from onions, as onions release ethylene gas, which speeds up the sprouting process. — Melissa Kravitz Hoeffner, Martha Stewart, 19 July 2026

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