What does vapor mean?
“Vapor” names a substance in gaseous form and, in everyday use, the visible mist or haze that may accompany it. The most familiar example is water vapor: water changes into an invisible gas when it evaporates, but condensation can produce a visible cloud of tiny droplets that people also call steam. In American English, “vapor” is the standard spelling; British English generally uses “vapour.” As a verb, “to vapor” means to give off vapor or become vapor, although this use is less frequent than the noun. In literary or figurative contexts, “vapors” can refer to things regarded as insubstantial, fanciful, or empty, such as idle talk or doomed plans. The word is useful scientifically because it distinguishes a substance’s gaseous state from its liquid or solid state, while its everyday associations with mist, humidity, and hot surfaces make it familiar and vivid.
A gas, especially water vapor, or a visible mist of tiny liquid droplets suspended in the air. In figurative use, the plural can refer to something insubstantial or merely empty.
"A thin vapor rose from the steaming pavement."
Technical definitions often reserve “vapor” for a substance in the gaseous state, distinguishing it from visible droplets formed by condensation.
To emit vapor or to evaporate into vapor.
"The water began to vapor in the heat."
This verb is less common than the noun and is particularly associated with American English; British English more often uses “vaporise.”
The plural is especially common in figurative senses referring to fanciful ideas, empty talk, or insubstantial concerns.
"He dismissed the plans as idle vapors."
Water vapor is invisible; what people often call visible steam is actually a cloud of tiny condensed droplets.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does vapor come from?
The word entered Middle English through Anglo-French, ultimately deriving from Latin vapor, meaning “steam” or “vapor.” Related English forms include “evaporate,” “evaporation,” and “vaporize,” all based on the same Latin root and its verb vaporare, “to steam” or “to emit vapor.” The modern American spelling reflects the Latin form more directly, while British English retained the spelling “vapour.”
Related word forms
How vapor is actually used
In technical contexts, vapor usually means a substance in the gaseous state, while the visible mist seen above hot water is more precisely a suspension of droplets. The verb is less common than the noun and is especially associated with American usage.
Easily confused with vapor
“Vapour” is the usual British English spelling, while “vapor” is the usual American English spelling of the same word.
Steam often refers specifically to water in gaseous form or to the visible mist produced by condensation, whereas vapor is a broader term that can refer to a gas or a suspended mist.