vapor

especially British, va·pour

[vey-per]

noun

1. a visible exhalation, such as fog, mist, steam, smoke, or noxious gas, diffused through or suspended in the air.

   The vapors rising from the bogs smelled muddy.

2. Physics.,  a gas at a temperature below its critical temperature.

3. a substance converted into a gaseous state for technical or medicinal uses.

4. a combination of gaseous particles of a substance and air.

5. Archaic.,  vapors,

   1. harmful exhalations formerly supposed to be produced within the body, especially in the stomach.

   2. mental or physical illness, such as depression or hypochondria, formerly supposed to result from such exhalations, especially in women.

6. Often Facetious.,  the vapors. a feeling of being overwhelmed with strong emotion.

   That guy gives the press the vapors every time he announces a new project.

7. Archaic.

   1. a strange, senseless, or fantastic notion.

   2. something insubstantial or transitory.

verb (used with object)

1. to cause to rise or pass off in, or as if in, vapor; vaporize.

2. Archaic.,  to affect with the vapors; depress.

verb (used without object)

1. to rise or pass off in the form of vapor.

2. to emit vapor or exhalations.

3. to talk or act grandiloquently, pompously, or boastfully; bluster.

vapor

/ ˈveɪpə /

noun

1. the US spelling of vapour

vapor

1. The gaseous state of a substance that is normally liquid or solid at room temperature, such as water that has evaporated into the air.

2. See more at vapor pressure See also water vapor

3. A faintly visible suspension of fine particles of matter in the air, as mist, fumes, or smoke.

4. A mixture of fine droplets of a substance and air, as the fuel mixture of an internal-combustion engine.

Usage

The words vapor and steam usually call to mind a fine mist, such as that in the jet of water droplets near the spout of a boiling teakettle or in a bathroom after a shower. Vapor and steam, however, refer to the gaseous state of a substance. The fumes that arise when volatile substances such as alcohol and gasoline evaporate, for example, are vapors. The visible stream of water droplets rushing out of a teakettle spout is not steam. As the gaseous state of water heated past its boiling point, steam is invisible. Usually, there is a space of an inch or two between the spout and the beginning of the stream of droplets. This space contains steam. The steam loses its heat to the surrounding air, then falls below the boiling point and condenses in the air as water droplets. All liquids and solids give off vapors consisting of molecules that have evaporated from the substance. In a closed system, the vapor pressure of these molecules reaches an equilibrium at which the substance evaporates from the liquid (or solid) and recondenses on it in equal amounts.

Other Word Forms

• vaporable adjective
• vaporability noun
• vaporer noun
• vaporless adjective
• vaporlike adjective

Word History and Origins

Origin of vapor¹

First recorded in 1325–75; Middle English vapour, from Latin vapor “steam,” of uncertain origin; akin to vapidus vapid ( def. ) and vappa “wine that has gone flat”; perhaps cognate with Greek kapnós “smoke” ( acapnia ( def. ) )

Example Sentences

As the smoke rises, water vapor in the air condenses at high altitudes, creating what is known as a pyrocumulus cloud, or fire cloud.

From Los Angeles Times

For example, in the case of EO, highly corrosive hydrogen fluoride vapor.

From BBC

The term is used among conspiracy theorists who believe that the contrails of vapor that can form behind an airplane’s engines are actually chemicals being distributed from high altitude.

From Salon

He said such storms, which roll in from the Pacific Ocean carrying massive amounts of water vapor, would typically be on a larger scale.

From Los Angeles Times

SpaceX is known around the Southland for its highly visible vapor trails as well as its sudden booms.

From Los Angeles Times

Related Words

• condensation 
• fog 
• gas 
• moisture 
• smog 
• smoke 
• steam