from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The gaseous state of a substance that is liquid or solid at room temperature.
  • noun A faintly visible suspension of fine particles of matter in the air, as mist, fumes, or smoke.
  • noun A mixture of fine droplets of a substance and air, as the fuel mixture of an internal-combustion engine.
  • noun Something insubstantial, worthless, or fleeting.
  • noun A fantastic or foolish idea.
  • noun Exhalations within a bodily organ, especially the stomach, supposed to affect the mental or physical condition. Used with the.
  • noun A nervous disorder such as depression or hysteria. Used with the.
  • intransitive verb To fill or cover with vapor.
  • intransitive verb To vaporize.
  • intransitive verb To give off vapor.
  • intransitive verb To evaporate.
  • intransitive verb To engage in idle, boastful talk.

from The Century Dictionary.

  • To pass off in the form of vapor; dissolve, as into vapor or thin air; be exhaled; evaporate.
  • To give out vapor, steam, or gas; emit vapors or exhalations; exhale; steam.
  • To boast or vaunt; bully; hector; brag; swagger; bounce.
  • To cause to pass into the state of vapor; cause to dissolve or disappear in or as in vapor, gas, thin air, or other unsubstantial thing.
  • To afflict or infect with vapors; dispirit; depress.
  • To bully; hector.
  • noun An exhalation of moisture; any visible diffused substance, as fog, mist, steam, or smoke, floating in the atmosphere and impairing its transparency.
  • noun In physics, the gaseous form which a solid or liquid substance assumes when sufficiently heated.
  • noun Effluence; influence.
  • noun Wind; flatulence.
  • noun In medicine, a class of remedies, officinal in the British pharmacopœia, which are to be applied by inhalation: such as vapor creasoti, a mixture of 12 minims of creosote in 8 fluidounces of boiling water, the vapor of which is to be inhaled.
  • noun Something unsubstantial, fleeting, or transitory; vain imagination; fantastic notion.
  • noun plural A hectoring or bullying style of language or conduct, adopted by ranters and swaggerers with the purpose of bringing about a real or mock quarrel.
  • noun plural A disease of nervous debility in which strange images seem to float hazily before the eyes, or appear as if real; hence, hypochondriacal affections; depression of spirit; dejection; spleen; “the blues”: a term much affected in the eighteenth century, but now rarely used.

from the GNU version of the Collaborative International Dictionary of English.

  • transitive verb To send off in vapor, or as if in vapor.
  • intransitive verb To pass off in fumes, or as a moist, floating substance, whether visible or invisible, to steam; to be exhaled; to evaporate.
  • intransitive verb rare To emit vapor or fumes.
  • intransitive verb To talk idly; to boast or vaunt; to brag.
  • noun (Physics) Any substance in the gaseous, or aëriform, state, the condition of which is ordinarily that of a liquid or solid.
  • noun In a loose and popular sense, any visible diffused substance floating in the atmosphere and impairing its transparency, as smoke, fog, etc.
  • noun obsolete Wind; flatulence.
  • noun Something unsubstantial, fleeting, or transitory; unreal fancy; vain imagination; idle talk; boasting.
  • noun An old name for hypochondria, or melancholy; the blues.
  • noun (Pharm.) A medicinal agent designed for administration in the form of inhaled vapor.
  • noun (Chem.) A small metallic drying oven, usually of copper, for drying and heating filter papers, precipitates, etc.; -- called also air bath. A modified form is provided with a jacket in the outside partition for holding water, or other volatile liquid, by which the temperature may be limited exactly to the required degree.
  • noun a burner for burning a vaporized hydrocarbon.
  • noun (Chem.) the relative weight of gases and vapors as compared with some specific standard, usually hydrogen, but sometimes air. The vapor density of gases and vaporizable substances as compared with hydrogen, when multiplied by two, or when compared with air and multiplied by 28.8, gives the molecular weight.
  • noun an engine worked by the expansive force of a vapor, esp. a vapor other than steam.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun Cloudy diffused matter such as mist, steam or fumes suspended in the air.
  • noun The gaseous state of a substance that is normally a solid or liquid.
  • verb intransitive To become vapor; to be emitted or circulated as vapor.
  • verb transitive To turn into vapor.
  • verb intransitive To use insubstantial language; to boast or bluster.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun the process of becoming a vapor
  • noun a visible suspension in the air of particles of some substance


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English vapour, from Anglo-Norman, from Latin vapor.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin vapor ("steam, heat").


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