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

The standard dressing at the 51-year-old stand consists of mustard, relish, onions, tomato, pickle spears, and celery salt, and adds lettuce, green peppers, and cucumber slices (hot peppers are available on request). — Amy Cavanaugh, Condé Nast Traveler, 4 Nov. 2026

Add sausage and onion; cook and stir until sausage is browned, about 5 minutes. — Maddy Bendgen, Better Homes & Gardens, 3 Nov. 2026

Cook 1 green bell pepper, halved, ribs and seeds removed, finely chopped, 1 medium white onion, finely chopped, and 2 celery stalks, finely chopped, in same skillet, stirring occasionally with a wooden spoon, until softened, about 4 minutes. — Inés Anguiano, Bon Appetit Magazine, 2 Nov. 2026

For those looking for a stew-like meal with winter approaching, the eatery serves Papaitan, a Filipino soup with meat, ginger, garlic, onions, Thai chili peppers and other animal organs. — Emma Hall, Sacbee.com, 2 Nov. 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
• French onion soup
• green onion
• onion dome
• onion ring
• onion soup
• 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