(organic chemistry) Any of the eighteen isomeric aliphatic hydrocarbons (C₈H₁₈) found in petroleum, especially an iso-octane 2,2,4 trimethyl-pentane; they are used as fuels and solvents.

plural of octane

A fever that recurs every eight days.

Occurring every eight days.

plural of octan

(astronomy) A small circumpolar constellation of the southern sky, said to resemble an octant. It lies closest to the southern celestial pole of any constellation.

(organic chemistry) The saturated aliphatic aldehyde having eight carbon atoms

(chemistry) Any isomer of octane except the normal, straight-chain one; especially 2,2,4-trimethylpentane.

(of fuel) Having a high octane number, good anti-knock characteristics; used in high performance vehicles. / (by extension) High powered, energetic, forceful or dynamic.

A measure of the antiknock properties of an automobile fuel; isooctane having an octane number of 100, a fuel with the same antiknock properties as a mixture of 90% isooctane and 10% heptane having an octane number of 90.