onion

on‧ion S3 /ˈʌnjən/ BrE AmE noun [uncountable and countable]
[Date: 1100-1200; Language: Old French; Origin: oignon, from Latin unio]
a round white vegetable with a brown, red, or white skin and many layers. Onions have a strong taste and smell:
Chop the onions finely.
red onions
home-made onion soup

Oxford Advanced Learner's Dictionary

onion

onion [onion onions] [ˈʌnjən] [ˈʌnjən] noun

countable, uncountable
a round vegetable with many layers inside each other and a brown, red or white skin. Onions have a strong smell and flavour
• Chop the onions finely.
• French onion soup
Word Origin:
Middle English: from Old French oignon, based on Latin unio(n-), denoting a kind of onion.
Example Bank:
• Garnish with a little chopped onion.
• Put the chopped onion and garlic in the pan…
• a jar of pickled onions
• cheese and onion flavoured crisps
• sage and onion stuffing

• the onion domes of St Basil's Cathedral

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

onion / ˈʌn.jən / noun [ C or U ]

onion

A2 a vegetable with a strong smell and flavour, made up of several layers surrounding each other tightly in a round shape, usually brown or red on the outside and white inside:

I always cry when I'm chopping onions.

Fry the onion and garlic for about two minutes.

Collins Advanced Learner’s English Dictionary

onion

/ʌnjən/
(onions)

An onion is a round vegetable with a brown skin that grows underground. It has many white layers on its inside which have a strong, sharp smell and taste.
It is made with fresh minced meat, cooked with onion and a rich tomato sauce.

N-VAR