va·​por | \ˈvā-pər \

Definition of vapor 

(Entry 1 of 2)

1 : diffused matter (such as smoke or fog) suspended floating in the air and impairing its transparency

2a : a substance in the gaseous state as distinguished from the liquid or solid state

b : a substance (such as gasoline, alcohol, mercury, or benzoin) vaporized for industrial, therapeutic, or military uses also : a mixture (such as the explosive mixture in an internal combustion engine) of such a vapor with air

3a : something unsubstantial or transitory : phantasm

b : a foolish or fanciful idea

4 vapors plural

a archaic : exhalations of bodily organs (such as the stomach) held to affect the physical or mental condition

b : a depressed or hysterical nervous condition


vapored; vaporing\ ˈvā-​p(ə-​)riŋ \

Definition of vapor (Entry 2 of 2)

intransitive verb

1a : to rise or pass off in vapor

b : to emit vapor

2 : to indulge in bragging, blustering, or idle talk

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Other Words from vapor


vaporer \ -​pər-​ər \ noun

Did You Know?


Speakers of the English language, mindful of the lightness and unsubstantiality of floating air and gas, have put several airy words to good use over the years to describe the act of talking idly or boastfully. The earliest such word is blow (as in "he kept blowing about his new job"), which drifted into English sometime about 1400. Vapor wafted into the language in the 1620s, and a little over 200 years later windbags, later also known as gasbags, not only blew and vapored but also gassed about anything they could.

Examples of vapor in a Sentence


a faded Southern belle tiresomely vaporing about all the handsome beaux she had in her long-ago youth

Recent Examples on the Web: Noun

Another option is to purchase a diffuser that emits an odorless vapor that mimics calming pheromones for dogs or cats, like the Comfort Zone Diffuser, suggests Nelson. Stephanie Eckelkamp, Good Housekeeping, "9 Tips For Keeping Your Pet Calm And Safe During Fireworks," 30 June 2017 The next step is to put the paper in a chamber that turns the ice into a vapor. Erik Lacitis, The Seattle Times, "Huge Aberdeen fire steals thousands of pieces of town history, including a Kurt Cobain exhibit," 16 June 2018 Volcanic smog, or air pollution, is created by vapor, carbon dioxide and sulfur dioxide gas released from Kilauea. CBS News, "Besides lava and ash, Hawaii volcano is pumping out hazardous "vog"," 28 May 2018 As subjects sat unmoving for several minutes, their images were exposed to the plates, which were then developed using heated mercury vapor and a gold chloride solution. Meilan Solly, Smithsonian, "Particle Accelerator Reveals Hidden Faces in Damaged 19th-Century Daguerreotype Portraits," 10 July 2018 White, hot vapor and blue fumes started emanating from cracks Thursday afternoon, Hawaii County officials said. Joe Sutton, CNN, "This isn't the first time volcanic lava has spread in Hawaii residential areas," 4 May 2018 Smog, also known as ground-level ozone, is formed by a reaction between sunlight and pollution from car tailpipes, power plants and factories, fumes from volatile solvents and gasoline vapors. Michael Hawthorne,, "EPA chief Pruitt overrules agency staff, gives Wisconsin's Walker, Foxconn big break on smog," 2 May 2018 Now a Stinger—a GT2 version deluxe ($50,100, as tested), with a throat-singing V6, rear-wheel drive, adaptive suspension, brakes for days—is sitting in front of my house, giving local dads the vapors. Dan Neil, WSJ, "2018 Kia Stinger GT2: The Best German Car to Come Out of South Korea," 6 Apr. 2018 Breathing in the vapors of essential oils may worsen some respiratory conditions., "Essential oils: Why 'natural' doesn't always mean safe," 22 May 2018

Recent Examples on the Web: Verb

But whole body cryotherapy exposes the body for a couple of minutes to vapor that has been supercooled to somewhere between minus 200 and minus 300 degrees Fahrenheit. Aaron E. Carroll, New York Times, "Cold Therapy? Maybe Better Save Your Money," 2 Jan. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'vapor.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of vapor


14th century, in the meaning defined at sense 1


15th century, in the meaning defined at sense 1a

History and Etymology for vapor


Middle English vapour, borrowed from Anglo-French & Latin; Anglo-French vapor, vapour, borrowed from Latin vapor, earlier vapōs "exhalation, steam, warmth," perhaps akin to Lithuanian kvãpas "smell, scent"

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Statistics for vapor

Last Updated

1 Nov 2018

Look-up Popularity

Time Traveler for vapor

The first known use of vapor was in the 14th century

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More Definitions for vapor



English Language Learners Definition of vapor

: a substance that is in the form of a gas or that consists of very small drops or particles mixed with the air


va·​por | \ˈvā-pər \

Kids Definition of vapor

1 : fine bits (as of fog or smoke) floating in the air and clouding it

2 : a substance in the form of a gas water vapor


variants: or chiefly British vapour \ ˈvā-​pər \

Medical Definition of vapor 

1a : a substance in the gaseous state as distinguished from the liquid or solid state

b : a substance (as alcohol or benzoin) vaporized for industrial, therapeutic, or military uses

2 vapors or chiefly British vapours plural

a : exhalations of bodily organs (as the stomach) formerly held to affect the physical or mental condition

b : a depressed or hysterical nervous condition

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Comments on vapor

What made you want to look up vapor? Please tell us where you read or heard it (including the quote, if possible).


playful or foolish behavior

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