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

Opening first on Saturday, May 9, is Buccan Sandwich Shop, a grab-and-go lunch concept that specializes in sandwiches like the popular beef carpaccio with arugula, Parmesan, crispy onions, mayo, lemon vinaigrette, as well as turkey club, Cubano and Buffalo chicken sandwiches. —Connie Ogle updated May 8, Miami Herald, 8 May 2026

Add the carrots and cook for another 5 to 6 minutes, or until the onions are soft and translucent. —Philip Potempa, Chicago Tribune, 8 May 2026

Cobalt and nickel move in next, followed finally by iron, which wraps the entire structure in a protective shell, in an onion-like arrangement. —Mrigakshi Dixit, Interesting Engineering, 7 May 2026

Add the onions, stirring to coat in the butter, then cook, stirring often, for 10 minutes. —Karla Walsh, Better Homes & Gardens, 6 May 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