n. [ OE. vapour, OF. vapour, vapor, vapeur, F. vapeur, L. vapor; probably for cvapor, and akin to Gr. &unr_; smoke, &unr_; to breathe forth, Lith. kvepti to breathe, smell, Russ. kopote fine soot. Cf. Vapid. ] [ Written also vapour. ] [ 1913 Webster ]

1. (Physics) Any substance in the gaseous, or aeriform, state, the condition of which is ordinarily that of a liquid or solid. [ 1913 Webster ]

☞ The term vapor is sometimes used in a more extended sense, as identical with gas; and the difference between the two is not so much one of kind as of degree, the latter being applied to all permanently elastic fluids except atmospheric air, the former to those elastic fluids which lose that condition at ordinary temperatures. The atmosphere contains more or less vapor of water, a portion of which, on a reduction of temperature, becomes condensed into liquid water in the form of rain or dew. The vapor of water produced by boiling, especially in its economic relations, is called steam. [ 1913 Webster ]

Vapor is any substance in the gaseous condition at the maximum of density consistent with that condition. This is the strict and proper meaning of the word vapor. Nichol. [ 1913 Webster ]

2. In a loose and popular sense, any visible diffused substance floating in the atmosphere and impairing its transparency, as smoke, fog, etc. [ 1913 Webster ]

The vapour which that fro the earth glood [ glided ]. Chaucer. [ 1913 Webster ]

Fire and hail; snow and vapors; stormy wind fulfilling his word. Ps. cxlviii. 8. [ 1913 Webster ]

3. Wind; flatulence. [ Obs. ] Bacon. [ 1913 Webster ]

4. Something unsubstantial, fleeting, or transitory; unreal fancy; vain imagination; idle talk; boasting. [ 1913 Webster ]

For what is your life? It is even a vapor, that appeareth for a little time, and then vanisheth away. James iv. 14. [ 1913 Webster ]

5. pl. An old name for hypochondria, or melancholy; the blues. “A fit of vapors.” Pope. [ 1913 Webster ]

6. (Pharm.) A medicinal agent designed for administration in the form of inhaled vapor. Brit. Pharm. [ 1913 Webster ]

Vapor bath. (a) A bath in vapor; the application of vapor to the body, or part of it, in a close place; also, the place itself. (b) (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. --
Vapor burner, a burner for burning a vaporized hydrocarbon. --
Vapor density (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. --
Vapor engine, an engine worked by the expansive force of a vapor, esp. a vapor other than steam. [ 1913 Webster ]

v. t. To send off in vapor, or as if in vapor; as, to vapor away a heated fluid. [ Written also vapour. ] [ 1913 Webster ]

He'd laugh to see one throw his heart away,
Another, sighing, vapor forth his soul. B. Jonson. [ 1913 Webster ]

v. i. [ imp. & p. p. Vapored p. pr. & vb. n. Vaporing. ] [ From Vapor, n.: cf. L. vaporare. ] [ Written also vapour. ] [ 1913 Webster ]

1. To pass off in fumes, or as a moist, floating substance, whether visible or invisible, to steam; to be exhaled; to evaporate. [ 1913 Webster ]

2. To emit vapor or fumes. [ R. ] [ 1913 Webster ]

Running waters vapor not so much as standing waters. Bacon. [ 1913 Webster ]

3. To talk idly; to boast or vaunt; to brag. [ 1913 Webster ]

Poets used to vapor much after this manner. Milton. [ 1913 Webster ]

We vapor and say, By this time Matthews has beaten them. Walpole. [ 1913 Webster ]

n. The quality or state of being vaporable. [ 1913 Webster ]

a. Capable of being converted into vapor by the agency of heat; vaporizable. [ 1913 Webster ]

v. i. [ L. vaporare, vaporatum. See Vapor. ] To emit vapor; to evaporate. [ R. ] [ 1913 Webster ]

n. [ Cf. F. vaporation, L. vaporatio. ] The act or process of converting into vapor, or of passing off in vapor; evaporation. [ R. ] [ 1913 Webster ]

a. 1. Wet with vapors; moist. [ 1913 Webster ]

2. Affected with the vapors. See Vapor, n., 5. [ 1913 Webster ]

n. One who vapors; a braggart. [ 1913 Webster ]

Vaporer moth. (Zool.) See Orgyia. [ 1913 Webster ]

. (Metal.) A process for coating metal (usually iron or steel) surfaces with zinc by exposing them to the vapor of zinc instead of, as in ordinary galvanizing, to molten zinc; -- called also Sherardizing. Vapor galvanizing is accomplished by heating the articles to be galvanized together with zinc dust in an air tight receptacle to a temperature of about 600° F., which is 188° below the melting point of zinc, or by exposing the articles to vapor from molten zinc in a separate receptacle, using hydrogen or other reducing gas to prevent oxidation. [ Webster 1913 Suppl. ]