water vapor

noun

1. a dispersion, in air, of molecules of water, especially as produced by evaporation at ambient temperatures rather than by boiling. Compare steam ( def 2 ).

water vapor

1. Water in its gaseous state, especially in the atmosphere and at a temperature below the boiling point. Water vapor in the atmosphere serves as the raw material for cloud and rain formation. It also helps regulate the Earth's temperature by reflecting and scattering radiation from the Sun and by absorbing the Earth's infrared radiation.
2. See also vapor

Word History and Origins

Origin of water vapor¹

First recorded in 1875–80

Example Sentences

So which influence wins out—increasing water vapor or decreasing wind shear?

From The Daily Beast

That's not including water vapor, of which there is a fair amount.

From Project Gutenberg

The Enterprise had taken damage in the last exchange; Koreff's spectroscopes showed her halo-ed with air and water vapor.

From Project Gutenberg

The next most abundant product of the fermentation is water vapor which can often be seen passing off in clouds of steam.

From Project Gutenberg

In the case just cited, the union of two volumes of hydrogen and one of oxygen results in precisely two volumes of water vapor.

From Project Gutenberg

The presence of some water vapor in the air is absolutely necessary to animal and plant life.

From Project Gutenberg