cetane numbercetane number
a number that increases with higher quality, representing the ignition properties of diesel engine fuel oils: it is determined by the percentage of cetane that must be mixed with a standard liquid to match the fuel oil's performance in a standard test engine
A performance rating for diesel fuels, with a higher number indicating greater fuel efficiency. The number corresponds to the percentage of cetane in a cetane-heptamethylnonane mixture, or (and originally) in a cetane-methylnaphthalene mixture, with the same ignition performance as the fuel being rated. Also called cetane rating.