vapor
Americannoun
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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.
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Physics. a gas at a temperature below its critical temperature.
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a substance converted into a gaseous state for technical or medicinal uses.
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a combination of gaseous particles of a substance and air.
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Archaic. vapors,
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harmful exhalations formerly supposed to be produced within the body, especially in the stomach.
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mental or physical illness, such as depression or hypochondria, formerly supposed to result from such exhalations, especially in women.
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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.
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Archaic.
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a strange, senseless, or fantastic notion.
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something insubstantial or transitory.
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verb (used with object)
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to cause to rise or pass off in, or as if in, vapor; vaporize.
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Archaic. to affect with the vapors; depress.
verb (used without object)
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to rise or pass off in the form of vapor.
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to emit vapor or exhalations.
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to talk or act grandiloquently, pompously, or boastfully; bluster.
noun
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The gaseous state of a substance that is normally liquid or solid at room temperature, such as water that has evaporated into the air.
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See more at vapor pressure See also water vapor
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A faintly visible suspension of fine particles of matter in the air, as mist, fumes, or smoke.
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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
Derived Forms
Inflected Forms
Nouns
Participles
Conjugated Forms
Present
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vaporsimple
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vaporssimple
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have vaporedperfect
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has vaporedperfect
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am vaporingprogressive
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are vaporingprogressive
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is vaporingprogressive
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have been vaporingperfect progressive
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has been vaporingperfect progressive
Past
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vaporedsimple
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had vaporedperfect
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was vaporingprogressive
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were vaporingprogressive
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had been vaporingperfect progressive
Future
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."
Vocabulary lists containing vapor
The Water Cycle - Introductory
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Earth Science - Middle School
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The Water Cycle - Middle School and High School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
The first approach uses hydrodynamic cavitation, which creates and collapses tiny vapor bubbles in contaminated water.
From Science Daily ● Jul. 20, 2026
Walking through the space, I passed between the steam room and saunas of the traditional vapor and infrared variety.
From The Wall Street Journal ● Jun. 9, 2026
The resulting vapor then traveled through a tube in which temperatures could be carefully controlled as the material cooled.
From Science Daily ● Jun. 3, 2026
At one point, the tank began bulging, and “it got to a point where it does what we call a BLEVE, which is a ‘boiling liquid expanding vapor explosion,’” Covey said Friday afternoon.
From Los Angeles Times ● May 23, 2026
A cup of coffee on the bureau top sent up a plume of vapor.
From "East of Eden" by John Steinbeck
Did he inhale too deeply the vapors of power?
From Slate ● Jul. 13, 2026
They were a toxic organization coasting on a grand arena and the vapors of memories.
From The Wall Street Journal ● Jun. 14, 2026
Southern California is bracing for a possible leak or explosion of toxic vapors from a damaged tank that has forced thousands of people to evacuate.
From The Wall Street Journal ● May 24, 2026
The evacuation is large in part due to the potential of a plume of toxic vapors.
From Los Angeles Times ● May 22, 2026
“Now then, now then, now then,” said Slughorn, whose massive outline was quivering through the many shimmering vapors.
From "Harry Potter and the Half-Blood Prince" by J.K. Rowling
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
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 Irving, Washington
High over all this billowing and peaking tower the Pitons of Carbet, gem-violet through the vapored miles,—the tallest one filleted with a single soft white band of cloud.
From Two Years in the French West Indies by Hearn, Lafcadio
For a time he stormed about the Moorish halls, and vapored about the bastions, and looked down fire and sword upon the palace of the captain-general.
From Journeys Through Bookland, Vol. 7 by Sylvester, Charles Herbert
"She needn't to have done that about her piano," vapored Mr. Vertrees.
From The Turmoil, a novel by Tarkington, Booth
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
Alone he faced the roystering Morton at Merrymount, unarming that vaporing rebel and putting his riotous colony upon its good behavior.
From Great Men and Famous Women. Vol. 1 A series of pen and pencil sketches of the lives of more than 200 of the most prominent personages in History by Horne, Charles F. (Charles Francis)
But we were the weakest when Slavery made us so loud-mouthed and vaporing; we shall be strongest when the cause of our boasting has disappeared.
From The Atlantic Monthly, Volume 15, No. 92, June, 1865 by Various
I trembled as I listened to this wild vaporing.
From The International Spy Being the Secret History of the Russo-Japanese War by Upward, Allen
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
