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[gas] /gæs/
noun, plural gases or gasses.
Physics. a substance possessing perfect molecular mobility and the property of indefinite expansion, as opposed to a solid or liquid.
any such fluid or mixture of fluids.
any such fluid used as an anesthetic, as nitrous oxide:
Did the dentist give you gas for your extraction?
any such combustible fluid used as fuel:
Light the gas in the oven.
  1. gasoline.
  2. Also called gas pedal. the foot-operated accelerator of an automotive vehicle:
    Take your foot off the gas.
Coal Mining. an explosive mixture of firedamp with air.
an aeriform fluid or a mistlike assemblage of fine particles suspended in air, used in warfare to asphyxiate, poison, or stupefy an enemy.
  1. empty talk.
  2. a person or thing that is very entertaining, pleasing, or successful:
    The party was an absolute gas, and we loved it.
  3. a person or thing that affects one strongly.
verb (used with object), gassed, gassing.
to supply with gas.
to overcome, poison, or asphyxiate with gas or fumes.
to singe (yarns or fabrics) with a gas flame to remove superfluous fibers.
to treat or impregnate with gas.
  1. to talk nonsense or falsehood to.
  2. to amuse or affect strongly:
    Her weird clothes really gas me.
verb (used without object), gassed, gassing.
to give off gas, as a storage battery being charged.
  1. to indulge in idle, empty talk.
  2. to become drunk (often followed by up).
Verb phrases
gas up, to fill the gasoline tank of an automobile, truck, or other vehicle.
step on the gas, Informal. to increase the speed of one's movement or activity; hurry:
We'd better step on the gas or we'll be late for the concert.
Origin of gas
1650-60; coined by J. B. van Helmont (1577-1644), Flemish chemist; suggested by Greek cháos atmosphere
Related forms
gasless, adjective
nongas, noun, plural nongases.
Can be confused
fluid, gas, liquid (see synonym study at liquid) Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for gasses
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British Dictionary definitions for gasses


noun (pl) gases, gasses
a substance in a physical state in which it does not resist change of shape and will expand indefinitely to fill any container. If very high pressure is applied a gas may become liquid or solid, otherwise its density tends towards that of the condensed phase Compare liquid (sense 1), solid (sense 1)
any substance that is gaseous at room temperature and atmospheric pressure
any gaseous substance that is above its critical temperature and therefore not liquefiable by pressure alone Compare vapour (sense 2)
  1. a fossil fuel in the form of a gas, used as a source of domestic and industrial heat See also coal gas, natural gas
  2. (as modifier): a gas cooker, gas fire
a gaseous anaesthetic, such as nitrous oxide
(mining) firedamp or the explosive mixture of firedamp and air
the usual US, Canadian, and New Zealand word for petrol See also gasoline
(informal) step on the gas
  1. to increase the speed of a motor vehicle; accelerate
  2. to hurry
a toxic or suffocating substance in suspension in air used against an enemy
(informal) idle talk or boasting
(slang) a delightful or successful person or thing: his latest record is a gas
(US) an informal name for flatus
verb gases, gasses, gassing, gassed
(transitive) to provide or fill with gas
(transitive) to subject to gas fumes, esp so as to asphyxiate or render unconscious
(intransitive) to give off gas, as in the charging of a battery
(transitive) (in textiles) to singe (fabric) with a flame from a gas burner to remove unwanted fibres
(informal) (intransitive) foll by to. to talk in an idle or boastful way (to a person)
(transitive) (slang, mainly US & Canadian) to thrill or delight
Derived Forms
gasless, adjective
Word Origin
C17 (coined by J. B. van Helmont (1577–1644), Flemish chemist): modification of Greek khaos atmosphere
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for gasses



1650s, from Dutch gas, probably from Greek khaos "empty space" (see chaos). The sound of Dutch "g" is roughly equivalent to that of Greek "kh." First used by Flemish chemist J.B. van Helmont (1577-1644), probably influenced by Paracelsus, who used khaos in an occult sense of "proper elements of spirits" or "ultra-rarified water," which was van Helmont's definition of gas.

Modern scientific sense began 1779, with later specialization to "combustible mix of vapors" (1794, originally coal gas); "anesthetic" (1894, originally nitrous oxide); and "poison gas" (1900). Meaning "intestinal vapors" is from 1882. "The success of this artificial word is unique" [Weekley]. Slang sense of "empty talk" is from 1847; slang meaning "something exciting or excellent" first attested 1953, from earlier hepster slang gasser in the same sense (1944). Gas also meant "fun, a joke" in Anglo-Irish and was used so by Joyce (1914). As short for gasoline, it is American English, first recorded 1905.



1886, "to supply with gas," from gas (n.). Sense of "poison with gas" is from 1889 as an accidental thing, from 1915 as a military attack. Related: Gassed; gassing.

Online Etymology Dictionary, © 2010 Douglas Harper
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gasses in Medicine

gas (gās)
n. pl. gas·es or gas·ses

  1. The state of matter distinguished from the solid and liquid states by relatively low density and viscosity, relatively great expansion and contraction with changes in pressure and temperature, the ability to diffuse readily, and the spontaneous tendency to become distributed uniformly throughout any container.

  2. A substance in the gaseous state.

  3. A gaseous fuel, such as natural gas.

  4. Gasoline.

  5. A gaseous asphyxiant, an irritant, or a poison.

  6. A gaseous anesthetic, such as nitrous oxide.

  7. Flatulence.

  8. Flatus.

v. gassed, gas·sing, gas·es or gas·ses
  1. To treat chemically with gas.

  2. To overcome, disable, or kill with poisonous fumes.

  3. To give off gas.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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gasses in Science
One of four main states of matter, composed of molecules in constant random motion. Unlike a solid, a gas has no fixed shape and will take on the shape of the space available. Unlike a liquid, the intermolecular forces are very small; it has no fixed volume and will expand to fill the space available.

gaseous adjective (gās'ē-əs, gāsh'əs)
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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gasses in Culture

gas definition

In physics, one of the phases of matter. The atoms or molecules in gases are more widely spaced than in solids or liquids and suffer only occasional collisions with one another.

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Slang definitions & phrases for gasses



  1. Empty and idle talk; mendacious and exaggerated claims; bullshit: Most of what I say is pure gas, my friend (1847+)
  2. Talk of any sort, esp conversation: Let's get together for a good gas (1852+)
  3. Denatured alcohol or some other substitute for liquor (1940s+ Hoboes)
  4. A fastball: He got him out on the high gas (1980s+ Baseball)
  5. gasser: ''What a gas!'' she cried on the way from the courthouse (1957+)
  6. Anabolic steroids, used to increase body bulk: He said about 60 percent of the wrestlers he knew during the 1980s used steroids, commonly known as ''juice'' or ''gas'' (1980s+ Athletes)


  1. Talked: I haven't gassed this long for a year
  2. To impress one's hearers very favorably; overcome with admiration: Bird gassed them/ She gassed me, she was that good (1940s+ Cool talk)
  3. To impress an audience very unfavorably; fail with: Our show appears to have gassed both the critics and the public (1970s+)

Related Terms

cook with gas, run out of gas, step on it

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Idioms and Phrases with gasses


In addition to the idiom beginning with
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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