From Middle English vapour, from Anglo-Norman vapour, Old French vapor, from Latin vapor.

• (RP) IPA: /ˈveɪpə/
• (America) IPA: /ˈveɪpɚ/

vapor (American spelling)

1. Cloudy diffused matter such as mist, steam or fumes suspended in the air.
2. The gaseous state of a substance that is normally a solid or liquid.
3. Something insubstantial, fleeting, or transitory; unreal fancy; vain imagination; idle talk; boasting.
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, James 4:14 ↗:

     For what is your life? It is even a vapour, that appeareth for a little time, and then vanisheth away.

4. (dated) Any medicinal agent designed for administration in the form of inhaled vapour.
5. (archaic, in the plural) Hypochondria; melancholy; the blues; hysteria, or other nervous disorder.
   • Jan 13, 1732, John Arbuthnot, letter to Jonathan Swift

     He talks me into a fit of vapours twice or thrice a week.

   • 1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, →OCLC ↗, page 188:

     She made several gulps and controlled her breath. She released her grip on Podson and stared at him without recognition. Podson went on patting her reassuringly, relieved from administering first aid to an attack of the vapours.

6. (obsolete) Wind; flatulence.
   • 1605, Francis Bacon, “(please specify |book=1 or 2)”, in The Twoo Bookes of Francis Bacon. Of the Proficience and Aduancement of Learning, Diuine and Humane, London: […] [Thomas Purfoot and Thomas Creede] for Henrie Tomes, […], →OCLC ↗:

     The surcharge of the stomack from a gross vapour, and from the poise of some outward weight, are alike

• French: vapeur
• German: Dampf
• Italian: gas, vapore
• Portuguese: vapor
• Russian: пар
• Spanish: vapor

vapor (vapors, present participle vaporing; simple past and past participle vapored) (American spelling)

1. (intransitive) To become vapor; to be emitted or circulated as vapor.
2. (transitive) To turn into vapor.

   to vapor away a heated fluid

   • 1617, Ben Jonson, Lovers Made Men:

     He'd […] laugh to see one throw his heart away, / Another, sighing, vapour forth his soul.

3. To emit vapor or fumes.
   • 1627 (indicated as 1626), Francis [Bacon], “(please specify the page, or |century=I to X)”, in Sylua Syluarum: Or A Naturall Historie. In Ten Centuries. […], London: […] William Rawley […]; [p]rinted by J[ohn] H[aviland] for William Lee […], →OCLC ↗:

     Running waters vapour not so much as standing waters.

4. (intransitive) To use insubstantial language; to boast or bluster.
   • 1904, “Saki”, ‘Reginald's Christmas Revel’, Reginald:

     then the Major gave us a graphic account of a struggle he had with a wounded bear. I privately wished that the bears would win sometimes on these occasions; at least they wouldn't go vapouring about it afterwards.

5. (transitive) To give (someone) the vapors; to depress, to bore.
   • 1782, Frances Burney, Cecilia, III.vi.9:

     “I only mean,” cried she, giddily, “that he might have some place a little more pleasant to live in, for really that old moat and draw-bridge are enough to vapour him to death […].”

• German: prahlen