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

Of course, all of these venues have access to the organic crops grown on-site in the garden pavilion, from onions and peppers to herbs and edible flowers; those hardworking pollinators in the bee hotel also supply fresh honey. —Condé Nast, Condé Nast Traveler, 23 May 2026

This sporty gastropub in the ‘burbs touts a $10 Cam’s Cheeseburger (regularly $20) all day Monday, a half-pound custom blend with American cheese, lettuce, tomato, onion, pickle and AP sauce with a separate drink purchase. —Phillip Valys, Sun Sentinel, 22 May 2026

Mix together with sautéed onion, ground beef, Italian sausage, plus marinara sauce and cheese, then top with extra shredded mozzarella and parmesan before baking. —Alana Al-Hatlani, Southern Living, 22 May 2026

Chives are part of the onion family and can have a very strong, oniony scent, which helps deter aphids—a common pest that targets basil. —Emily Hayes, Martha Stewart, 21 May 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