AskDefine | Define onion

Dictionary Definition



1 edible bulb of an onion plant
2 bulbous plant having hollow leaves cultivated worldwide for its rounded edible bulb [syn: onion plant, Allium cepa]
3 an aromatic flavorful bulb

User Contributed Dictionary



Latin unio


  • /ˈʌnjən/
  • /"Vnj@n/


  1. A monocotyledonous plant of genus Allium allied to garlic, used as vegetable and spice.
  2. The bulb of such a plant.
  3. The genus as a whole.
  4. A ball.
  5. In the context of "colloquial|chiefly|archaic": A person from Bermuda or of Bermudian descent.
a monocotyledonous plant of genus Allium allied to garlic, used as vegetable and spice.
the bulb

Extensive Definition

Onion is a term used by many plants in the genus Allium. They are known by the common name "onion" but, used without qualifiers, it usually refers to Allium cepa. Allium cepa is also known as the garden onion or 'bulb' onion and 'shallot'.
Allium cepa is known only in cultivation, but related wild species occur in Central Asia. The most closely-related species include Allium vavilovii Popov & Vved. and Allium asarense R.M. Fritsch & Matin from Iran. However Zohary and Hopf warn that "there are doubts whether the vavilovii collections tested represent genuine wild material or only feral derivatives of the crop."


Onions, one of the oldest vegetables known to mankind, are found in a bewildering array of recipes and preparations, spanning almost the totality of the world's cultures; they are nowadays available in fresh, frozen, canned, pickled, and dehydrated forms. Onions can be used, usually chopped or sliced, in almost every type of food, including cooked foods and fresh salads, and as a spicy garnish; they are rarely eaten on their own but usually act as accompaniment to the main course. Depending on the variety, an onion can be sharp, spicy, tangy and pungent or mild and sweet.
Onions pickled in vinegar are eaten as a snack. These are often served as a side serving in fish and chip shops throughout the United Kingdom. Onions are a staple food in India, and are therefore fundamental to Indian cooking. They are commonly used as a base for curries, or made into a paste and eaten as a main course or as a side dish.
Tissue from onions is frequently used in science education to demonstrate microscope usage, because they have particularly large cells which are readily observed even at low magnifications.

Historical uses

It is thought that bulbs from the onion family have been used as a food source for millennia. In Caananite Bronze Age settlements, traces of onion remains were found alongside fig and date stones dating back to 5000 BC. Onion is native to South Asia, and is widely used in Indian cuisine. However, it is not clear if these were cultivated onions. Archaeological and literary evidence such as the Book of Numbers 11:5 suggests cultivation probably took place around two thousand years later in ancient Egypt, at the same time that leeks and garlic were cultivated. Workers who built the Egyptian pyramids may have been fed radishes and onions. believing that its spherical shape and concentric rings symbolized eternal life. Onions were even used in Egyptian burials as evidenced by onion traces being found in the eye sockets of Ramesses IV. They believed that if buried with the dead, the strong scent of onions would bring breath back to the dead.
In ancient Greece, athletes ate large quantities of onion because it was believed that it would lighten the balance of blood. Roman gladiators were rubbed down with onion to firm up their muscles. In the Middle Ages onions were such an important food that people would pay for their rent with onions and even give them as gifts.

Medicinal properties and health benefits

Wide-ranging claims have been made for the effectiveness of onions against conditions ranging from the common cold to heart disease, diabetes, osteoporosis, and other diseases. They contain chemical compounds believed to have anti-inflammatory, anticholesterol, anticancer, and antioxidant properties such as quercetin. However, it has not been demonstrated that increased consumption of onions is directly linked to health benefits.
In many parts of the world, onions are used to heal blisters and boils. A traditional Maltese remedy for sea urchin wounds is to tie half a baked onion to the afflicted area overnight. In the morning, the spikes will be in the onion. In the United States, products that contain onion extract are used in the treatment of topical scars; some studies have found their action to be ineffective, while others found that they may act as an anti-inflammatory or bacteriostatic and can improve collagen organization in rabbits.
Onions may be especially beneficial for women, who are at increased risk for osteoporosis as they go through menopause, by destroying osteoclasts so that they do not break down bone.

Onions and eye irritation

As onions are sliced, cells are broken, allowing enzymes called alliinases to break down amino acid sulphoxides and generate sulphenic acids. Sulphenic acids are unstable and spontaneously rearrange into a volatile gas called syn-propanethial-S-oxide. The gas diffuses through the air and eventually reaches the eye, where it reacts with the water to form a diluted solution of sulphuric acid. This acid irritates the nerve endings in the eye, making them sting. Tear glands produce tears to dilute and flush out the irritant.
Supplying ample water to the reaction or chewing gum while peeling onions prevents the gas from reaching the eyes. Eye irritation can, therefore, be avoided by cutting onions under running water or submerged in a basin of water. Rinsing the onion and leaving it wet while chopping may also be effective. Another way to avoid irritation is by not cutting off the root of the onion, or by doing it last, as the root of the onion has a higher concentration of enzymes. Using a sharp blade to chop onions will limit the cell damage and the release of enzymes that drive the irritation response. (Having a sharp knife and keeping the root of a halved onion on until the end also reduces the risk of cutting yourself if your knife slips). Chilling or freezing onions prevents the enzymes from activating, limiting the amount of gas generated. Having a fire, such as a candle or a burner, will help as the heat and flames will draw in the onion gas, burn it, and then send it up with the rest of the flame exhaust. In the heat, the chemical changes such that it no longer irritates the eyes. The volume of sulfenic acids released, and the irritation effect, differs among Allium species.
On January 31, 2008, the New Zealand Crop and Food institute led by Colin Eady created 'no tears' onions by using Australian gene-silencing biotechnology.


  • Bulb onion - Grown from seed (or onion sets), bulb onions range from the pungent varieties used for dried soups and onion powder to the mild and hearty sweet onions, such as the Vidalia from Georgia or Walla Walla from Washington that can be sliced and eaten on a sandwich instead of meat.
  • Multiplier onions - Raised from bulbs which produce multiple shoots, each of which forms a bulb.
  • Tree onion or Egyptian onion - Produce bulblets in the flower head; a hybrid of Allium cepas.
  • Welsh onion or Green onion
Shallots and ten other onion (Allium cepa L.) varieties commonly available in the United States were evaluated: Western Yellow, Northern Red, New York Bold, Western White, Peruvian Sweet, Empire Sweet, Mexico, Texas 1015, Imperial Valley Sweet, and Vidalia. In general, the most pungent onions delivered many times the benefits of their milder cousins.
Shallots have the most phenols, six times the amount found in Vidalia onion, the variety with the lowest phenolic content. Shallots also have the most antioxidant activity, followed by Western Yellow, New York Bold, Northern Red, Mexico, Empire Sweet, Western White, Peruvian Sweet, Texas 1015, Imperial Valley Sweet, and Vidalia. Western Yellow onions have the most flavonoids, eleven times the amount found in Western White, the variety with the lowest flavonoid content.
For all varieties of onions, the more phenols and flavonoids they contain, the more antioxidant and anti-cancer activity they provide. When tested against liver and colon cancer cells, Western Yellow, New York Bold and shallots were most effective in inhibiting their growth. The milder-tasting varieties—Western White, Peruvian Sweet, Empire Sweet, Mexico, Texas 1015, Imperial Valley Sweet, and Vidalia—showed little cancer-fighting ability.

Production trends

Onions in language

In the English vernacular, "an onion" is a difficult situation, the use stemming from the onion's tendency to irritate or inflame the eyes. Conversely, the term "onion" can be used to describe any state of being, as in the phrase, "[someone] really dices my onion!" It may also represent an object of many layers.
In some Scots dialects, onion is pronounced 'Ingin'.
An "Onion" is also an old slang term to decribe a person from Bermuda; a Bermudian. Bermuda is known to sprout some of best onions in the world, that is why they're (Bermudians) called "onions".
Feminist poet Carol Ann Duffy uses the onion as a metaphor of love and relationships in her poem "Valentine" (1993), one of the poems in her collection "Mean time"
Expressions referring to "layers of the onion" evoke the process of peeling back the layers of something (a person, reality, etc.), without however reaching a core - the centre of the onion being simply another layer. The metaphor is thus used to challenge the notion that there is a core/essence 'behind' surface layers, stressing the continuity between layer and core. Due to the number of layers in an onion it can also be used simply to evoke complexity - something having 'many layers', or 'always another layer behind this one".
This idea was used (& twisted) in the first Shrek movie, (Dreamworks LLC), when Shrek tries to explain to his partner, Donkey, that he is a complex person by telling him that 'Ogres are like onions.' (meaning that they have layers), to which Donkey replies 'Oh I get it. You leave them out in the sun too long and they go all brown and start sprouting little white hairs!'
In other languages too the onion has acquired different connotations, eg., amongst the Khasi tribe in North East India, Onion or "piat" in the local dialect refers to someone who is present everywhere or in every social gathering.



  • Sen, Colleen T. (2004). Food culture in India. Greenwood Publishing. ISBN 0313324875.

See also

onion in Arabic: بصل
onion in Guarani: Sevói
onion in Aymara: Siwilla
onion in Min Nan: Chhang-thâu
onion in Belarusian (Tarashkevitsa): Цыбуля
onion in Bulgarian: Кромид лук
onion in Catalan: Ceba
onion in Czech: Cibule kuchyňská
onion in Danish: Løg
onion in German: Zwiebel
onion in Estonian: Sibul
onion in Modern Greek (1453-): Κρεμμύδι
onion in Spanish: Allium cepa
onion in Esperanto: Cepo
onion in Basque: Tipula
onion in Persian: پیاز
onion in French: Oignon
onion in Friulian: Civole
onion in Scottish Gaelic: Uinnean
onion in Galician: Cebola
onion in Korean: 양파
onion in Hindi: प्याज़
onion in Upper Sorbian: Kobołk
onion in Indonesian: Bawang Bombay
onion in Italian: Allium cepa
onion in Hebrew: בצל הגינה
onion in Kinyarwanda: Inkoko
onion in Haitian: Zonyon
onion in Kurdish: Pîvaz
onion in Latin: Cepa
onion in Lithuanian: Valgomasis svogūnas
onion in Hungarian: Vöröshagyma
onion in Marathi: कांदा
onion in Malay (macrolanguage): Bawang
onion in Dutch: Ui (bolgewas)
onion in Dutch Low Saxon: Uui
onion in Japanese: タマネギ
onion in Norwegian Nynorsk: Lauk
onion in Occitan (post 1500): Ceba
onion in Polish: Cebula zwyczajna
onion in Portuguese: Cebola
onion in Kölsch: Öllisch
onion in Romanian: Ceapă
onion in Quechua: Siwilla
onion in Russian: Репчатый лук
onion in Albanian: Qepa
onion in Slovak: Cesnak cibuľový
onion in Slovenian: Čebula
onion in Serbian: Црни лук
onion in Finnish: Keltasipuli
onion in Swedish: Lök (art)
onion in Telugu: ఉల్లిపాయ
onion in Thai: หอมใหญ่
onion in Vietnamese: Hành tây
onion in Tonga (Tonga Islands): Onioni
onion in Turkish: Soğan
onion in Vlaams: Andjoen
onion in Yiddish: צוויבל
onion in Chinese: 洋蔥
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