Definition of octane number
: a number that is used to measure the antiknock properties of a liquid motor fuel (as gasoline) with a higher number indicating a smaller likelihood of knocking —called also octane rating — compare cetane number
First Known Use of octane number
Learn More about octane number
Britannica.com: Encyclopedia article about "octane number"
Seen and Heard
What made you want to look up octane number? Please tell us where you read or heard it (including the quote, if possible).