# octane

/ˈɑkteɪn/ (US) · /ˈɒkteɪn/ (UK) · CEFR C2 · Noun

Source: https://englishreference.com/word/octane
Updated: 2026-05-09

## Definition

a number that shows how well fuel burns in a car engine. A higher number usually means the fuel is better for high-performance cars.

For teachers: a figure indicating the anti-knock properties of a fuel, based on the percentage of iso-octane in a reference mixture. Often used metaphorically to describe the intensity or power of an activity.

## Examples

- Most cars run perfectly well on standard octane fuel.
- The mechanic recommended using a higher octane gasoline to prevent the engine from making a knocking sound.
- The film's high-octane action sequences left the audience breathless, though critics argued the plot lacked the intellectual depth found in the director's earlier, more contemplative works.

## Usage notes

- Uncountable when referring to the chemical property; countable when referring to specific fuel grades.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.