vapor

Short definition from Wiktionary

Noun

1. 1
   Cloudy diffused matter such as mist, steam or fumes suspended in the air.
2. 2
   The gaseous state of a substance that is normally a solid or liquid.
3. 3
   Something insubstantial, fleeting, or transitory; unreal fancy; vain imagination; idle talk; boasting.
4. 4
   Any medicinal agent designed for administration in the form of inhaled vapour.
5. 5
   Hypochondria; melancholy; the blues; hysteria, or other nervous disorder.
6. 6
   Wind; flatulence.

Verb

1. 1
   To become vapor; to be emitted or circulated as vapor.
2. 2
   To turn into vapor.
3. 3
   To emit vapor or fumes.
4. 4
   To use insubstantial language; to boast or bluster.
5. 5
   To give (someone) the vapors; to depress, to bore.