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

Full Sun Soil Type: Dry to Medium, Well-draining, Average Fertility Soil pH: Mildly Acidic to Neutral (6.0-7.0) Ornamental onions or alliums add a punch of color to the garden and serve as an interesting upright element. —Kim Toscano, Southern Living, 29 Mar. 2025

Vegetables like broccoli, tomatoes, mushrooms, onions, kale and asparagus are also included in most low-carb diets—as are eggs, cheese, Greek yogurt and nuts like walnuts, peanuts, macadamia nuts and pistachios. —Daryl Austin, USA Today, 29 Mar. 2025

Tuesday, April 1, Ground Beef and Bean Chili, with cheese and onion, whole grain cornbread, Romaine Salad and tomatoes, mixed fruit, milk. —Ramona Sentinel, San Diego Union-Tribune, 26 Mar. 2025

Mesa County Public Health was the agency that first investigated last year’s E. coli outbreak linked with raw onions in McDonald’s Quarter Pounders, which sickened at least 104 people, killing one, across 14 states. —Jacqueline Howard, CNN Money, 26 Mar. 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