vapor

n. (brit. Vapour) 1 moisture or other substance diffused or suspended in air, e.g. Mist, smoke. 2 gaseous form of a substance. 3 medicinal inhalant.  vaporous adj. Vapoury adj. [latin vapor steam]

n. Any substance in the gaseous, or aeriform, state, the condition of which is ordinarily that of a liquid or solid.