What does gaseous mean?
Gaseous is an adjective describing matter that exists in the form of a gas rather than as a liquid or solid. Its clearest use is scientific: a substance is gaseous when it exists as a gas under the conditions being discussed. The word can also mean resembling gas, although this sense is less common and may be qualified by a phrase such as “gaseous cloud” or “gaseous envelope.” Gaseous matter includes atmospheric gases, steam, and many chemical compounds, so the word frequently appears in discussions of temperature, pressure, emissions, planetary atmospheres, and energy. Its tone is formal and factual, especially in scientific and environmental contexts. Although a gas occupies a definite volume and may flow or expand, “gaseous” specifically identifies its physical state rather than suggesting something is merely airy, faint, or unconvincing. Gaseous is therefore useful when precision matters, particularly when distinguishing a substance’s state from its color, smell, concentration, or behavior.
adjectiveExisting in the state of a gas; consisting of gas. In some contexts, it means resembling gas in form or character.
- Existing in the state of a gas; consisting of gas.
- Resembling gas in form, appearance, or character.
"The compound remains gaseous at room temperature."
"Hydrogen is a gaseous element under standard conditions."
"The report described the planet's upper atmosphere as a thick, gaseous layer of hydrogen and helium."
Gaseous gives a precise name to the invisible state in which gases such as oxygen, carbon dioxide, and helium exist.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does gaseous come from?
Gaseous was formed in the 17th century from the word “gas” and the suffix “-eous,” which contributes the sense “of the nature of” or “resembling.” The word “gas” itself entered English in the 17th century, having been coined by the Flemish physician and chemist Jan Baptista van Helmont through New Latin and ultimately Greek “khaos,” meaning “chaos.” The adjective gaseous developed within the scientific vocabulary of early modern chemistry as writers began systematically describing matter by its physical state.
Related word forms
How gaseous is actually used
Gaseous is especially common in scientific, technical, and formal writing. It should not be confused with the less formal “gassy,” which can mean full of gas or smelling of gas.