atmós

atmós is the Greek noun ατμός, meaning vapor or steam. In classical and modern Greek, it designates the gaseous phase of matter or a visible emission of vapor, such as steam from hot water. The term functions as a basic lexical item in Greek and also serves as the etymon for a widely used scientific prefix in many languages.

Etymology and linguistic notes: The word derives from Ancient Greek ατμός (atmós). From this noun, the English and international prefix atmo- is formed, appearing in numerous scientific terms that relate to air, vapor, or gas. In Greek, compounds built with this root preserve the sense of vapour or atmosphere, for example in references to steam or atmospheric phenomena.

Usage and scope: In scientific and educational contexts, atmo- is the productive prefix that appears in words such as atmosphere, atmospheric, and atmo- in other compound terms across disciplines like physics, chemistry, and meteorology. While atmós itself is a common noun in Greek, it is seldom used as a standalone term in scientific writing in English; the prefix atmo- and the noun atmosphere are far more prevalent in multilingual usage.

See also: atmosphere; atomos (ἄτομος) meaning indivisible, a different Greek root; atmo- (prefix).