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 lamb is cooking, thinly slice the remaining onion half and transfer to a medium bowl. — Kate Williams, AJC.com, 27 July 2026

For breakfast, alongside omelettes, porridge, and granola, try the traditional savoury dish katogo of mashed matoke with onions and tomatoes, meat optional. — Condé Nast, Condé Nast Traveler, 27 July 2026

Davis combines sautéed onions, bell peppers, shredded potatoes, and eggs in her batches. — Randi Gollin, Martha Stewart, 26 July 2026

Their sandwiches come mini, 8-inch or 12-inch and as classic cheesesteaks with steak, onions and cheese or with specialty toppings. — Katelyn Umholtz, Kansas City Star, 24 July 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