When something that is normally liquid — like water — becomes a visible, gas-like substance floating in the air, it's a vapor.

The fog that often settles across your town in the mornings is one kind of vapor. Mist is also a vapor, as is your frozen breath when you can see it on a cold winter day. The Latin root word is vaporem, "exhalation, steam, or heat."

Definitions of vapor
  1. noun
    a visible suspension in the air of particles of some substance
    synonyms: vapour
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    water at boiling temperature diffused in the atmosphere
    water vapor, water vapour
    water in a vaporous form diffused in the atmosphere but below boiling temperature
    live steam
    steam coming from a boiler at full pressure
    water in small drops in the atmosphere; blown from waves or thrown up by a waterfall
    type of:
    a mixture in which fine particles are suspended in a fluid where they are supported by buoyancy
  2. noun
    the process of becoming a vapor
    synonyms: evaporation, vaporisation, vaporization, vapour
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    the application of heat to change something from a liquid to a gas
    clouding, clouding up
    the process whereby water particles become visible in the sky
    smoke, smoking
    a hot vapor containing fine particles of carbon being produced by combustion
    decoction mashing, decoction process
    (brewing) a process in which part of the mash is removed and boiled and then returned
    type of:
    phase change, phase transition, physical change, state change
    a change from one state (solid or liquid or gas) to another without a change in chemical composition
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