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

Don’t put corn husks, coffee grinds, onion peels, peach pits, eggshells, bones, vegetable peels, meat scraps, grease and large amounts of pasta down the drain. —Jessica Elliott, Dallas Morning News, 10 Feb. 2026

Grapes, raisins, chocolate, gum, anything with xylitol in it, onions, and garlic, can all be harmful to your animal. —Angela Hatem, Parents, 10 Feb. 2026

Nothing says comfort like a juicy burger, and this version is extra delicious thanks to buttery baked onions. —Mary Alice Russell, Southern Living, 10 Feb. 2026

Once the onions are soft and golden-brown, beat together cream cheese, sour cream, and mayo. —Sophia Beams, Better Homes & Gardens, 8 Feb. 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