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 phaseCompare liquid (def. 1), solid (def. 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 aloneCompare vapour (def. 2)
a fossil fuel in the form of a gas, used as a source of domestic and industrial heatSee also coal gas, natural gas
(as modifier)a gas cooker; gas fire
a gaseous anaesthetic, such as nitrous oxide
miningfiredamp or the explosive mixture of firedamp and air
the usual US, Canadian, and New Zealand word for petrol See also gasoline
step on the gasinformal
to increase the speed of a motor vehicle; accelerate
a toxic or suffocating substance in suspension in air used against an enemy
informalidle talk or boasting
slanga delightful or successful person or thinghis latest record is a gas
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.
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.
A substance in the gaseous state.
A gaseous fuel, such as natural gas.
A gaseous asphyxiant, an irritant, or a poison.
A gaseous anesthetic, such as nitrous oxide.
To treat chemically with gas.
To overcome, disable, or kill with poisonous fumes.
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.