Gas definitions and example sentences on Wordnik

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Definitions (59)

American Heritage Dictionary (16)

noun 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.
noun A substance in the gaseous state.
noun A gaseous fuel, such as natural gas.

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Century Dictionary (33)

A substance possessing perfect molecular mobility and the property of indefinite expansion. The term was originally synonymous with air, but was afterward applied to substances supposed (but wrongly—see below) to be incapable of reduction to a liquid or solid state. In accordance with this use a gas was defined to be a permanently elastic fluid or air differing from common air. According to the kinetic theory of gases, now accepted, the molecules of a gas are in a state of rapid motion in right lines, constantly colliding with one another and with the walls of any containing vessel, and hence exerting pressure against them. For example, in the case of air at ordinary temperatures it is calculated that the average velocity of the molecules is about that of a rifle-bullet as it leaves the gun. If a gas is compressed into less volume, the number of impacts against the sides of the containing vessel is increased, and hence the pressure or tension increases, and conversely (Boyle's law). The temperature, according to this theory, is the average kinetic energy of a molecule; hence, increased temperature brings increased momentum, and so increased pressure on the walls of the vessel. This theory also explains many of the phenomena of viscosity, diffusion, etc. By increased pressure and diminished temperature (at least below the critical point) any gas can be reduced to the liquid form, the amount of pressure and degree of cold required differing widely with different gases. The so-called fixed or permanent gases, which were long supposed to be incoercible, as hydrogen, oxygen, nitrogen, etc., yield only to extreme conditions of cold and pressure. There is no essential difference between a gas and a vapor (see vapor), but for convenience the latter name is given to the gaseous form of substances which under the ordinary conditions of temperature and pressure are liquids or solids. Vapors and the gases most easily liquefied deviate most widely from Boyle's law, that the volume is inversely proportional to the pressure, and also from the law of the constant increment of expansion with increase of temperature. Gases are distinguished from liquids by the name of elastic fluids, because of their power of indefinite expansion. (See liquid.) The number of gaseous bodies is great, and they differ greatly in their chemical properties. They are all, however, susceptible of combining chemically with fluid and solid substances. Some of them are of great importance in the arts and manufactures, as, for example, carbonic acid or carbon dioxid, sulphurous acid or sulphur dioxid, and coal-gas. Gases are ordinarily invisible. That such subterraneal steams will easily mingle with liquors, and imbue them with their own qualities, may be inferred from the experiment of mixing the gas (as the Helmontians call it), or the scarce coagulable fumes of kindled and extinguished brimstone, with wine, which is thereby long preserved. Boyle, Origin and Virtues of Gems, ii. Gases are distinguished from other forms of matter, not only by their power of indefinite expansion so as to fill any vessel, however large, and by the great effect which heat has in dilating them, but by the uniformity and simplicity of the laws which regulate their changes. Clerk Maxwell, Heat, p. 31.
Specifically In coal-mining, any explosive mixture of fire-damp with common air.
In popular language, a compound of various gases, used for illuminating and heating purposes. It is some form of carbureted hydrogen artificially made and distributed by pipes to points of consumption. The common kind is coal-gas, obtained from bituminous coals by carbonization in retorts at a high temperature. A carbureted hydrogen gas, called water-gas, resulting from the passing of steam through a mass of incandescent carbon and the subsequent admixture of hydrocarbons or other enriching substances, is also used. Oil-gas is an illuminating gas obtained by the distilling at high temperature of petroleum or other liquid hydrocarbons.

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Examples (50)

This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry. — Latest Articles
I hope to take this into some gas-filled region, where the gas will be able to leak in, but the air won't. — The Black Star Passes
In pure air there is a good kind of gas which is necessary to keep us alive; this gas is called oxygen When air is taken into the lungs, the oxygen mixes with the blood in them and makes it pure. — Object Lessons on the Human Body A Transcript of Lessons Given in the Primary Department of School No. 49, New York City
Pressure raises the fusing point of rocks, and the weight of the crust may keep the interior in what may be called a solid state, although so hot as to be a liquid or a gas were the pressure to be removed THE INTERIOR OF THE EARTH IS RIGID AND HEAVY. — The Elements of Geology
[8] Portions of the gas were also confined in portable vessels of tinned iron, from which it was burned when required, thus forming a moveable gas-light. — Men of Invention and Industry

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fuel · chemical · oxygen · fluid · steam · heat · smoke · energy · metal · vapor · gasoline · air

Roget's II: The New Thesaurus, Third Edition by the Editors of the American Heritage® Dictionary. Copyright © 2003, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Etymologies (3)

American Heritage Dictionary (1)

Dutch, an occult physical principle supposed to be present in all bodies, alteration of Greek khaos, chaos, empty space, coined by Jan Baptista van Helmont (1577-1644), Flemish chemist.

Century Dictionary (2)

A word invented by the Belgian chemist Van Helmont (died 1644), who expressly says “Hunc spiritum, incognitum hactenus, novo nomine gas voco” (this vapor, hitherto unknown, I call by a new name, gas). The word came into general use: D. G. Danish Swedish gas, F. Portuguese gaz, Spanish Italian gas, Russian gasŭ, Hindustani gās, etc. Various guesses have been made at the word which might possibly have suggested the particular syllable gas, as D. geest (Anglo-Saxon gāst, English ghost), spirit; German gäscht, froth, foam; Swedish gäsa, ferment, efferversce; French gaze, gauze, etc.
from gas, n.

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