Octane

How to spell octane

6 letters · 2 syllables

How to pronounce octane

Say the part in capitals loudest.

What does octane mean?

1. nounA rating of a fuel's resistance to premature ignition, or the hydrocarbon that gives the rating its name.

Octane in a sentence

• The sports car runs best on high octane fuel.

• The label on the pump lists the octane rating for each grade.

Where does octane come from?

Language of origin: Greek

Octane is a modern chemistry coinage that joins the ancient number word for eight to a systematic suffix. The 'oct-' part traces back through the Latin octo to the Greek okto, both meaning simply 'eight', the same root that gives us 'octagon' and 'October' (once the eighth month of the Roman calendar). The '-ane' ending is a deliberate naming convention introduced by chemists in the nineteenth century to label the alkanes, a family of saturated hydrocarbons. Octane therefore literally means 'the eight one', because the molecule C8H18 is built around a chain of eight carbon atoms. The word entered everyday speech in the twentieth century thanks to the petrol industry, where 'octane rating' became the familiar measure of how well a fuel resists knocking; remembering that it begins with the same 'oct' that means eight keeps the spelling steady.

How the word is built

• oct- (from Latin/Greek for 'eight')
• -ane (chemistry suffix marking a saturated hydrocarbon, an alkane)