1. Any substance in the gaseous, or aeriform, state, the condition of which is ordinarily that of a liquid or solid.
  2. In a loose and popular sense, any visible diffused substance floating in the atmosphere and impairing its transparency, as smoke, fog, etc.
  3. Wind; flatulence.
  4. Something unsubstantial, fleeting, or transitory; unreal fancy; vain imagination; idle talk; boasting.
  5. An old name for hypochondria, or melancholy; the blues.
  6. A medicinal agent designed for administration in the form of inhaled vapor.
  7. To pass off in fumes, or as a moist, floating substance, whether visible or invisible, to steam; to be exhaled; to evaporate.
  8. To emit vapor or fumes.
  9. To talk idly; to boast or vaunt; to brag.

v. t.

  1. To send off in vapor, or as if in vapor; as, to vapor away a heated fluid.