water vapor

American  

noun

water vapors plural

1. a dispersion, in air, of molecules of water, especially as produced by evaporation at ambient temperatures rather than by boiling.

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water vapor Scientific  

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

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Other Word Forms

Noun Inflected Forms

• water vapors
  plural

Etymology

Origin of water vapor

First recorded in 1875–80

Example Sentences

The season’s rainstorm brought a sky as blue as a newborn’s eyes, but water vapor is still rising from the multicolored canopies.

From Los Angeles Times • Mar. 12, 2026

Looking at the past 30 years, the ensemble simulations showed an overall rise in atmospheric water vapor linked to increasing global temperatures.

From Science Daily • Feb. 15, 2026

Farther from the sun, water freezes into ice, which is easier for growing planets to collect than water vapor.

From Science Daily • Jan. 31, 2026

That storm turned water vapor into ice at natural gas wellheads, blocking fuel production.

From Barron's • Jan. 21, 2026

Its air is thin, containing mostly carbon dioxide but also some molecular nitrogen and argon and very small quantities of water vapor, oxygen and ozone.

From "Cosmos" by Carl Sagan