AskDefine | Define oily

Dictionary Definition

oily adj
1 containing an unusual amount of grease or oil; "greasy hamburgers"; "oily fried potatoes"; "oleaginous seeds" [syn: greasy, sebaceous, oleaginous]
2 unpleasantly and excessively suave or ingratiating in manner or speech; "buttery praise"; "gave him a fulsome introduction"; "an oily sycophantic press agent"; "oleaginous hypocrisy"; "smarmy self-importance"; "the unctuous Uriah Heep" [syn: buttery, fulsome, oleaginous, smarmy, unctuous]
3 coated or covered with oil; "oily puddles in the streets"
4 smeared or soiled with grease or oil; "greasy coveralls"; "get rid of rubbish and oily rags" [syn: greasy] [also: oiliest, oilier]

User Contributed Dictionary



From oil + -y.



  1. Relating to oil.
  2. Smeared with or containing oil.
  3. Excessively friendly or polite so as to sound insincere.


relating to oil
smeared with or containing oil
Excessively friendly or polite

Extensive Definition

An oil is a substance that is in a viscous liquid state ("oily") at ambient temperatures or slightly warmer, and is both hydrophobic, (immiscible with water, lit. water fearing) and lipophilic (miscible with other oils, literally "fat loving"''). This general definition includes compound classes with otherwise unrelated chemical structures, properties, and uses, including vegetable oils, petrochemical oils, and volatile essential oils. Oil is a nonpolar substance.


Oil is a non-scientific term used to refer to certain diverse and unrelated compounds sharing the same physical properties (such as viscosity and a hydrophobic nature), while ignoring related compounds. The compounds found in cooking oil are chemically very similar, almost identical, to those found in butter and very different from those found in diesel fuel, but while diesel is an oil, butter is not. Indeed diesel is once again very similar to natural gas, but gas is certainly not oil. This disparity stems partly from the fact that oils must be liquid at room temperature, and thus only certain liquid chemicals in many unrelated families are recognised, collectively, as 'oil'. Scientists, instead of using the term 'oil', adopt the terms lipids and other terms to denote them instead.

Types of oils

Mineral oil

All oils, with their high carbon and hydrogen content, can be traced back to organic sources or space. Mineral oils, found in porous rocks underground, are no exception, as they were originally the organic material, such as dead plankton, accumulated on the seafloor in geologically ancient times. Through various geochemical processes this material was converted to mineral oil, or petroleum, and its components, such as kerosene, paraffin waxes, gasoline, diesel and such. These are classified as mineral oils as they do not have an organic origin on human timescales, and are instead derived from underground geologic locations, ranging from rocks, to underground traps, to sands.
Other oily substances can also be found in the environment, the most well-known being asphalt, occurring naturally underground or, where there are leaks, in tar pits .
Petroleum and other mineral oils, (specifically labelled as petrochemicals), have become such a crucial resource to human civilization in modern times they are often referred to by the ubiquitous term of 'oil' itself.

Organic oils

Oils are also produced by plants, animals and other organisms through organic processes, and these oils are remarkable in their diversity. Oil is a somewhat vague term to use chemically, and the scientific term for oils, fats, waxes, cholesterol and other oily substances found in living things and their secretions, is lipids.
Lipids, ranging from waxes to steroids, are somewhat hard to characterize, and are united in a group almost solely based on the fact that they all repel, or refuse to dissolve, in water, and are however comfortably miscible in other liquid lipids. They also have a high carbon and hydrogen content, and are considerably lacking in oxygen compared to other organic compounds and minerals.


Food oils

Many edible vegetable and animal oils, and also fats, are used for various in cooking and food preparation. In particular, many foods are fried in oil much hotter than boiling water. Oils are also used for flavoring and for modifying the texture of foods e.g Stir Fry.
Health advantages are claimed for a number of specific oils such as omega 3 oils (fish oil, flaxseed oil, etc) and evening primrose oil.
Trans fats, often produced by hydrogenating vegetable oils, are known to be harmful to health.


Almost all oils burn in air generating heat, which can be used directly, or converted into other forms of energy by various means, for example, heating water into steam which is funneled into a turbine which turns a huge magnet. This spins and generates electricity. Oils are used as fuels for heating, lighting (e.g. kerosene lamp), powering combustion engines, and other purposes. Oils used for this purpose nowadays are usually derived from petroleum, (fuel oil, diesel oil, petrol (gasoline), etc), though biological oils such as biodiesel are gaining market share.

Heat transport

Many oils have higher boiling points than water and are electrical insulators, making them useful for liquid cooling systems, especially where electricity is used.


Due to their non-polarity, oils do not easily adhere to other substances. This makes oil useful as lubricant for various engineering purposes. Mineral oils are more suitable than biological oils, which degrade rapidly in most environmental conditions.


Color pigments can be easily suspended in oil, making it suitable as supporting medium for paints. The slow drying process and miscibility of oil facilitates a realistic style. This method has been used since the 15th century.


Crude oil can be processed into plastics and other substances.

Other Usages

Sulfuric acid has been called oil of vitriol in pre-scientific times, due to its syrupy consistency. Even in modern times, sulfuric acid is sometimes called vitriolic acid, and caustic personalities are called "vitriolic." Sulfuric acid is not a petrochemical, and in modern parlance, is not an oil.


Oils have been used throughout history as a fragrant or religious medium. Oil is often seen as a spiritually purifying agent. It is used in religious ceremonies, such as chrism or baptism.


See also

  • Emulsifier, allow oils and water to mix
  • Oil pollution
  • Wax, compounds with oil-like properties that are solid at common temperature
oily in Arabic: زيت
oily in Aragonese: Azeite
oily in Catalan: Oli
oily in Czech: Olej
oily in Welsh: Olew
oily in Danish: Olie
oily in German: Öle
oily in Modern Greek (1453-): Λάδι
oily in Spanish: Aceite
oily in Esperanto: Oleo
oily in Basque: Olio
oily in Persian: روغن
oily in French: Huile
oily in Scottish Gaelic: Ola
oily in Galician: Aceite
oily in Croatian: Ulja
oily in Ido: Oleo
oily in Indonesian: Minyak
oily in Icelandic: Olía
oily in Italian: Olio
oily in Hebrew: שמן
oily in Kongo: Mafuta
oily in Ladino: Azete
oily in Lithuanian: Aliejus
oily in Lingala: Mafúta
oily in Malay (macrolanguage): Minyak
oily in Dutch: Olie
oily in Japanese: 油
oily in Norwegian: Olje
oily in Norwegian Nynorsk: Olje
oily in Polish: Olej
oily in Portuguese: Óleo
oily in Russian: Масло
oily in Simple English: Oil
oily in Slovenian: Olje
oily in Sundanese: Minyak
oily in Finnish: Öljy
oily in Swedish: Olja
oily in Thai: น้ำมัน
oily in Ukrainian: Олія
oily in Yiddish: אויל
oily in Chinese: 油

Synonyms, Antonyms and Related Words

Privacy Policy, About Us, Terms and Conditions, Contact Us
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2
Material from Wikipedia, Wiktionary, Dict
Valid HTML 4.01 Strict, Valid CSS Level 2.1