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

Meanwhile, add another spoonful of frita sauce, some onion, and a pile of papitas to the burgers. — ABC News, 7 Oct. 2026

The dishes by executive chef Sander Bierenbroodspot often contain Dutch ingredients, such as the Old Amsterdam cheese in the gnocchi with truffle and egg or shrimp served with halibut, mashed potato, and roasted onion. — Condé Nast, Condé Nast Traveler, 6 Oct. 2026

Garlic and onions contain sulfur compounds that circulate through the body and are released through breath, sweat and even the pores. — Samantha Agate, Charlotte Observer, 6 Oct. 2026

Why Garlic and Onions Are the Usual Suspects Garlic and onions earn their reputation because of their chemistry. — Samantha Agate, Fort Worth Star-Telegram, 6 Oct. 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