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

By now your vegetable garden should be all planned out and seeds purchased, or at least ordered, as well as onion sets or plants, seed potatoes and sweet potato slips. —Dr. Matthew Lisy, Hartford Courant, 21 June 2025

Amy Westerman's blog Food Adventures With Amy expanded the description: the chicken was cut into small cubes and the dish also included shiitake mushrooms, onions and black bean chile sauce. —Kelly Brant, Arkansas Online, 17 June 2025

While there are many variations of this popular street food, its base is grilled spiced meat (usually chicken, lamb or beef) shaved from the rotisserie and tucked into a light sleeve of pita bread, topped with things such as tomatoes, onions and parsley and perhaps tahini sauce and hot sauce, too. —Cnn.com Wire Service, Mercury News, 16 June 2025

Add onion and cook until onion is tender, about 5 minutes longer. —Philip Potempa, Chicago Tribune, 13 June 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