オクタンFreq.FrequencyTop 100,000Meanings1nounoctanechemistryChemical term for the hydrocarbon C₈H₁₈; commonly encountered in the context of fuel and octane ratings.オクタン価かの高たかいガソリンはエンジンのノッキングを防ふせぐ。Gasoline with a high octane rating prevents engine knocking.