va·por (vāˈpər)

1. Barely visible or cloudy diffused matter, such as mist, fumes, or smoke, suspended in the air.
2. The state of a substance that exists below its critical temperature and that may be liquefied by application of sufficient pressure.
3. The gaseous state of a substance that is liquid or solid under ordinary conditions.
4. The vaporized form of a medicinal preparation to be administered by inhalation.
5. A mixture of a vapor and air, as an explosive mixture of gasoline and air burned in an internal-combustion engine.
6. vapors Exhalations within an organ, especially the stomach, supposed to affect the mental or physical condition. No longer in technical use.
7. vapors A nervous disorder such as depression or hysteria. No longer in technical use.