Definition of onion in English:


Line breaks: onion
Pronunciation: /ˈʌnjən


1A swollen edible bulb used as a vegetable, having a pungent taste and smell and composed of several concentric layers: cook the onion in the oil until lightly coloured [as modifier]: onion rings
More example sentences
  • In another saucepan cook the garlic and spring onions in the vegetable oil until the onion is soft but not brown.
  • Sweat the onion and diced vegetables in a little olive oil, they should soften and turn golden without browning.
  • To relieve the tension we joked about going home to the smell of grilled onions and peppers.
2The plant that produces the onion, with long rolled or strap-like leaves and spherical heads of greenish-white flowers.
  • Allium cepa, family Liliaceae (or Alliaceae)
More example sentences
  • Well I didn't get around to planting the onions last night, but I did dig up the second potato barrel.
  • Bend over the leaves of spring-sown onions just above the neck of each bulb, to help the ripening process.
  • Plant it among the cabbages and with onions and carrots to repel carrot fly.


Middle English: from Old French oignon, based on Latin unio(n-), denoting a kind of onion.


know one's onions

informal Be very knowledgeable about something: Fred knows his onions about Social Credit
More example sentences
  • When it comes to real ales and strong continental lagers the landlord really knows his onions, having been lured away from the Fat Cat in Norwich, a pub which wins major awards every single year.
  • There's room here for a few mavericks, including Canadian and Argentine labels, and - should you not know your onions - the young and friendly staff are happy to pass on their own top tips.
  • And you need to know your onions when you tackle Beethoven, even before you get to the details of the music.



More example sentences
  • The latter are smoky, but not too smoky; fresh, not crispy; sticky with an oniony, chili-flecked syrup - and flavorful enough that they don't need the ranch.
  • The saucy, oniony beans and yellow rice make it homey.
  • I use them around the garden as companion plants, which means I'm never without the oniony component of salads, soups and stews.

Definition of onion in: