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 bakers love experimenting with everything-but-the-kitchen-sink creations like a Wagyu Pastrami Cup (Wagyu pastrami, Parmesan, potato, mozzarella) and an Asparagus Bacon Danish (onion, black pepper, Philadelphia cream cheese, Swiss cheese). — John Metcalfe, Mercury News, 10 Aug. 2026

Finely chop the bell peppers, onion, and the parsley leaves and tender stems. — ABC News, 10 Aug. 2026

Baked onions are topped with lemon jam and fruits, while mussels come with capers and wind fennel gathered nearby, and the wine list draws heavily on Tinian Vineyards. — Monica Mendal, Vogue, 10 Aug. 2026

Enjoy a Dover sole in lemon and caper butter, or a white onion tart with mushroom ragout. — Roger Sands, Forbes.com, 10 Aug. 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