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

While the bread on the bottom soaks up all the flavor, the casserole is also topped with more bread and Gruyère to create that classic, bubbly golden crust French onion soup is known for. —Cameron Beall, Southern Living, 1 Nov. 2025

French-friend onions aren’t part of the line-up either. —Karla Walsh, Better Homes & Gardens, 1 Nov. 2025

It should be cooked thoroughly and not raw, trimmed of excess fat, cut into bite-sized pieces appropriate for the dog’s size and free from dog toxins such as garlic, onion or excessive salt. —Alice Gibbs, MSNBC Newsweek, 31 Oct. 2025

The burger consists of two steakburger patties, American cheese, pickles, onions and ketchup on a bun stamped with the Bitcoin symbol. —Cheryl V. Jackson, IndyStar, 31 Oct. 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