the gas form of a substance that is generally a solid or liquid at room temperature; not the same as aerosols or mists, which are composed of tiny droplets of liquid suspended in air
va·pour vapours in AM, use vapor Vapour consists of tiny drops of water or other liquids in the air, which appear as mist. water vapour. a mass of very small drops of a liquid which float in the air, for example because the liquid has been heated