vapor

American  

[vay-per] / ˈveɪ pər /

especially British, vapour

noun

• vapors
  plural

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.

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verb (used with object)

• vapors,
  present (3rd person singular)
• vapored,
  past participle,  past
• vaporing
  present participle

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)

• vapors,
  present (3rd person singular)
• vapored,
  past participle,  past
• vaporing
  present participle

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 British  

/ ˈveɪpə /

noun

1. the US spelling of vapour

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vapor Scientific  

/ vā′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 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.

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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

Derived Forms

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

Inflected Forms

Nouns

• vapors
  plural

Participles

• vaporing
  present
• vapored
  past

Conjugated Forms

Present

• vapor
  simple
• vapors
  simple
• have vapored
  perfect
• has vapored
  perfect
• am vaporing
  progressive
• are vaporing
  progressive
• is vaporing
  progressive
• have been vaporing
  perfect progressive
• has been vaporing
  perfect progressive

Past

• vapored
  simple
• had vapored
  perfect
• was vaporing
  progressive
• were vaporing
  progressive
• had been vaporing
  perfect progressive

Future

• will vapor
  simple
• will have vapored
  perfect
• will be vaporing
  progressive
• will have been vaporing
  perfect progressive

Etymology

Origin of vapor

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” ( see acapnia ( def. ))

Explanation

When something that is normally liquid — like water — becomes a visible, gas-like substance floating in the air, it's a vapor. The fog that often settles across your town in the mornings is one kind of vapor. Mist is also a vapor, as is your frozen breath when you can see it on a cold winter day. The Latin root word is vaporem, "exhalation, steam, or heat."

Example Sentences

See Examples For:

vapor vapors vapored vaporing

Essentially, cloud seeding speeds up the natural process of water vapor condensing inside of clouds.

From BBC ● Oct. 7, 2026

In particular, it strengthened the transport of water vapor from the midlatitude Indian Ocean toward East Antarctica through atmospheric rivers.

From Science Daily ● Sep. 6, 2026

“That vapor in the coastal zone is going to make conditions more humid,” Gershunov said.

From Los Angeles Times ● Aug. 28, 2026

Condensation occurs when water vapor changes into liquid water.

From Science Daily ● Aug. 23, 2026

She was holding two swords—long bronze scimitars that glowed with a weird greenish aura, boiling wisps of vapor that smelled sour and hot even across the yard.

From "The Battle of the Labyrinth" by Rick Riordan

The argument they’re advancing, as I can tell, is constructed out of preemption vapors.

From Slate ● Oct. 5, 2026

Did he inhale too deeply the vapors of power?

From Slate ● Jul. 13, 2026

In response to questions from The Times, the Orange County Healthcare Agency said it did not dispute statements that chemical vapors were released from the pressurized tank on May 21.

From Los Angeles Times ● Jun. 4, 2026

Tens of thousands told to evacuate as a tank of methyl methacrylate at an aerospace plastics facility poses a risk of leaking potentially toxic vapors in the air.

From Los Angeles Times ● May 23, 2026

Othello’s shout of pain echoes through the auditorium, and in the rows ahead of us a few of the ladies get the vapors.

From "Dread Nation" by Justina Ireland

The Tribune must have more "kick," so it vapored about "a few daring New Yorkers" venturing into the "far West," discovering Chicago and telling their friends about it.

From Time Magazine Archive

"She needn't to have done that about her piano," vapored Mr. Vertrees.

From The Turmoil, a novel by Booth Tarkington

So Sube vapored on hoping wildly that something would occur to him.

From Sube Cane by Edward Bellamy Partridge

The warriors were evidently baffled by these precautions, and, having smoked their pipe, and vapored off their valor, took their departure.

From Astoria, or, anecdotes of an enterprise beyond the Rocky Mountains by Washington Irving

He raged and vapored and threatened on the floor of the House.

From A History of the Four Georges and of William IV, Volume III by Justin McCarthy

The press was busy vaporing upon the significance of a de Valera free to roam the Free State.

From Time Magazine Archive

Apparently the only contribution Fiver could make was this beetle-spirited vaporing.

From "Watership Down: A Novel" by Richard Adams

They became very insolent and boastful, and would sharpen their knives and tomahawks upon the door-sills of the colonists, vaporing in mysterious phrase of the great deeds they were about to perform.

From King Philip Makers of History by John S. C. (John Stevens Cabot) Abbott

Brown, either do this, or cease your empty vaporing against the proscriptive features of our system, as you are pleased to style it.

From Americanism Contrasted with Foreignism, Romanism, and Bogus Democracy in the Light of Reason, History, and Scripture; In which Certain Demagogues in Tennessee, and Elsewhere, are Shown Up in Their True Colors by William Gannaway Brownlow

One might well excuse Walpole if he became sometimes a little impatient of the attitudinizing and the vaporing of the Patriots.

From A History of the Four Georges, Volume II by Justin McCarthy

Related Words

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