vapor
n. C / Un. a gas-like substance that comes from a liquid or solid, such as steam or smoke. You often see it in the air when water gets hot or when something burns.
n. a substance in the gaseous state that is typically liquid or solid at room temperature. Often used to describe visible moisture or fumes suspended in the air.
Water vapor rises from the pan as the water boils.
The mechanic warned that the gasoline vapor in the garage could be dangerous if someone lit a match.
As the temperature dropped rapidly overnight, the water vapor in the atmosphere condensed into a thick fog that blanketed the valley floor until sunrise.
From Middle English vapour, from Anglo-Norman vapour, Old French vapor, from Latin vapor (“steam, heat”).
Uncountable when referring to the substance generally; countable when referring to specific types of fumes or gases.