Definition of vapor

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