View synonyms for vapor


[ vey-per ]


  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. vapors, Archaic.
    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. the vapors. Often Facetious. 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.


/ ˈveɪpə /


  1. the US spelling of vapour


/ pər /

  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 pressureSee 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.

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Other Words From

  • va·por·a·ble adjective
  • va·por·a·bil·i·ty [vey-per-, uh, -, bil, -i-tee], noun
  • va·por·er noun
  • va·por·less adjective
  • va·por·like adjective

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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 ) )

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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.

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Example Sentences

Warmer oceans and air increase the evaporation of water vapor into the air, fueling a more potent storm.

They are heating up so much that their rock turns to vapor as they fall.

The platinum generates heat by combusting any methanol vapor that comes in contact with it.

They then used vapor deposition to grow nanowires inside these pores made from perovskite, a type of photosensitive compound used in solar cells.

Battelle’s system turns a 35-percent solution of hydrogen peroxide into a vapor.

As a result, the vapor measurements Mahar obtained are likely the best-case scenario.

Back then there were no vapor cigarettes for you simulate smoking.

If you plan to take in vapor in such amounts, you have to get juice with a low nicotine content to avoid poisoning yourself.

And the business of science, medicine, and faith itself is to restore or at least to prop up hope, that most complex vapor.

The color palette in Batman Begins is something I brought to the party, too—that rusty, sodium-vapor color.

Should the vapor not condense well, the test-tube may be immersed in a glass of cold water.

He crouched, nerves and muscles tense, controled in spite of the torturous cloud of scalding vapor that pressed close to him.

An exceedingly few rays of the sun, concentrated by a burning mirror, will convert gold and platina into vapor.

Nor would a planet, covered over for ages with a thick screen of vapor, be a novelty yet in the universe.

He loosed the blankets from his shoulders, and floundering down the slope was lost in the vapor.





vapidvapor barrier