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A numerical representation of the antiknock properties of motor fuel, compared with a standard reference fuel, such as isooctane, which has an octane number of 100. Also called octane rating.
(Chemistry) a measure of the quality of a petrol expressed as the percentage of isooctane in a mixture of isooctane and n-heptane that gives a fuel with the same antiknock qualities as the given petrol
a designation of antiknock quality of gasoline, numerically equal to the percentage of isooctane by volume in a mixture of isooctane and normal heptane that matches the given gasoline in antiknock characteristics. Also called oc′tane rat`ing.
octane number, octane rating
n → Oktanzahl f