combustion

The word “combustion” means the chemical process of burning, in which a substance reacts with oxygen to release heat and light. In plain terms, the scientific process of burning — fuel reacting with oxygen to release energy.

“Combustion” is pronounced kuhm-BUHS-chuhn (/kəmˈbʌs.t͡ʃən/ in IPA).

Here is “combustion” used in a sentence: “Combustion inside the engine's cylinders drives the pistons.”

“Combustion” is a noun.

The word “combustion” comes from Latin. From Old French combustion, from Latin combustio, from comburere ("to burn up").

“Combustion” is an uncommon word in modern English, usually learned at around the C2 level.

Combustion is the underlying chemical reaction in which a substance combines with oxygen to release heat and light, while fire is the visible, physical result of that reaction. Every fire involves combustion, but combustion can also occur without visible flame, as in slow oxidation.

Combustion is generally described as complete, where a substance burns fully with plenty of oxygen and produces mainly carbon dioxide and water, or incomplete, where limited oxygen leads to byproducts like carbon monoxide and soot. Engineers and scientists also distinguish rapid combustion, such as an explosion, from slow combustion, such as rusting.

Combustion requires a fuel, an oxidizer (usually oxygen), and enough heat to start the reaction, a combination often called the fire triangle. Remove any one of these three elements and the combustion process stops.