gas

The word “gas” means a state of matter, like air, that has no fixed shape or volume and spreads to fill its container. In plain terms, air-like matter that spreads out to fill any space, or (informally) fuel for a car.

“Gas” is pronounced gas (/ɡæs/ in IPA).

Here is “gas” used in a sentence: “Helium is a gas that is lighter than air.”

Depending on how it is used, “gas” can be a noun and a verb.

The word “gas” dates back to around 1600 and comes from Greek. Coined in the 1600s by the chemist Jan Baptist van Helmont, adapted from the Greek word "chaos.".

“Gas” is a very common word in modern English, usually learned at around the A2 level.

“Gas” has 5 distinct senses listed in this dictionary. The most common is: a state of matter, like air, that has no fixed shape or volume and spreads to fill its container.

Both are gaseous, but the terms differ. A gas is a substance that is naturally in the gaseous state at ordinary temperatures, like oxygen. A vapour is the gaseous form of something usually liquid or solid at those temperatures, such as water vapour from boiling water. The distinction is about normal conditions.

Matter commonly exists in three states: solid, liquid and gas. A solid holds a fixed shape and volume, a liquid keeps its volume but takes the shape of its container, and a gas has neither fixed shape nor volume, spreading to fill any space. Plasma is often listed as a fourth state.

The air we breathe is a mixture of gases, mainly nitrogen and oxygen. Other everyday examples include helium in balloons, carbon dioxide in fizzy drinks, and natural gas used for heating and cooking. Each has no fixed shape or volume and spreads out to fill its container.

It depends on where you are. In American English, 'gas' is short for gasoline, the fuel used in cars, which British English calls petrol. In science, and in British usage generally, 'gas' means a state of matter such as air. The intended meaning is usually clear from context.