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

All of the tacos come topped with raw diced onions and cilantro to cut through the richness; each bite is flavorful, balanced, and satisfying. —Natalie Hoy, Southern Living, 19 Oct. 2025

Lomo saltado, a uniquely Peruvian steak stir-fry, which traditionally comes with French fries, is plated with the fries hidden beneath tender meat and onions, soaking up all the flavorful drippings and making an accompanying portion of fluffy white rice seem nearly unnecessary. —Helen Rosner, New Yorker, 19 Oct. 2025

Add Brussels sprouts, sweet potato and onion to the skillet. —Bethany Thayer, Freep.com, 18 Oct. 2025

Cooked onions, peppers, chicken, ground beef and shredded beef were at improper holding temperatures. —Camila Pedrosa, Sacbee.com, 17 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