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 mix is finished with a few more ingredients like garlic and onion powders as well as jalapeño peppers. —Sam Stone, Bon Appetit Magazine, 20 Jan. 2026

While onions thrive in a cool, dark environment, leeks require refrigeration to stay fresh. —Riley Wofford, Martha Stewart, 20 Jan. 2026

Add onion and ¼ teaspoon of the salt; cook over medium heat, stirring occasionally, until translucent, 4 to 5 minutes. —Sabrina Weiss, PEOPLE, 19 Jan. 2026

At its core, this soup is carrots and onion sautéed in oil, simmered in stock, and blended until creamy. —Cameron Beall, Southern Living, 19 Jan. 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