onion

[ uhn-yuhn ]

noun

1. a plant, Allium cepa, of the amaryllis family, having an edible, succulent, pungent bulb.
2. any of certain similar plants.
3. the bulb of the onion plant.
4. the flavor or odor of this bulb.
5. Slang. a person:

   He's a tough onion.

adjective

1. containing or cooked with onions:

   onion soup.

2. of, relating to, or resembling an onion.

onion

/ ˈʌnjən /

noun

1. an alliaceous plant, Allium cepa, having greenish-white flowers: cultivated for its rounded edible bulb
2. the bulb of this plant, consisting of concentric layers of white succulent leaf bases with a pungent odour and taste
3. any of several related plants similar to A. cepa, such as A. fistulosum (Welsh onion)
4. know one's onions slang.
   know one's onions to be fully acquainted with a subject

Derived Forms

• ˈoniony, adjective

Other Words From

• onion·like adjective
• onion·y adjective

Word History and Origins

Origin of onion¹

1325–75; Middle English onyon < Old French oignon < Latin ūniōn- (stem of ūniō ) a unity, large pearl, onion; union

Word History and Origins

Origin of onion¹

C14: via Anglo-Norman from Old French oignon, from Latin unio onion, related to union

Idioms and Phrases

Idioms

1. know one's onions, Slang. to know one's subject or business thoroughly; be capable or proficient.

More idioms and phrases containing onion

see know one's stuff (onions) .

Example Sentences

Add the onion and cook, stirring often, until softened, about 2 minutes.

From Washington Post

The neurons’ other ends, called axons, stretch upward, passing through special passages inside the skull all the way to the brain, leading to the region called the olfactory bulb, named so for its onion-like shape.

From Nautilus

Add the onion and cook, stirring frequently, until golden brown, about 6 minutes.

From Washington Post

The onions should fall apart, creating a thick, rich sauce that coats the meat.

From Washington Post

In a 12-inch cast-iron skillet, or other oven-safe pan, add the sliced onion, spreading it on the bottom.

From Washington Post

Combine the beans and onion sauce in a 9x9-inch casserole dish and bake for 20 to 25 minutes.

From The Daily Beast

Onion routers refers to the TOR network, a system that allows users to mask their location and communicate anonymously online.

From The Daily Beast

Instead, it reminded me of a headline that once ran in The Onion: “Drunken Man Makes Interesting Point About Society.”

From The Daily Beast

I confess a particular weakness for his chocolate biscuits and pork pate with onion marmalade.

From The Daily Beast

Rub pork loin with paprika, Cajun seasoning, parsley, onion powder, garlic powder, sugar, salt, and pepper.

From The Daily Beast

Near the rue Monge there is a small café and restaurant, a place celebrated for its onion soup and its chicken.

From Project Gutenberg

Small Olive Blue,—wings Starling's feather stained with onion peelings,—yellow silk for body,—legs olive stained hackle.

From Project Gutenberg

But my opportunity finally came through the humble instrumentality of an onion.

From Project Gutenberg

Put it into a stewpan with an onion, a carrot, a piece of celery; cover with water and boil slowly for fifty minutes.

From Project Gutenberg

Mince an onion; take about a dozen peppercorns, twenty juniper berries, three bayleaves, and put these into a gill of vinegar.

From Project Gutenberg