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Glite Dictionary
octane number

octane number

6.4
A number that shows how well fuel resists knocking in car engines
  • noun
  • /ˈɑkˌteɪn ˈnʌmbər/
  • Specialized
translation icon : número de octano
  • The gasoline at this station has a high octane number, making it suitable for performance vehicles.

Examples

  • Racing cars often require gasoline with a higher octane number to prevent engine knocking.

  • Many drivers are advised to use fuel with the correct octane number for their car's engine.

  • What is the octane number of this gasoline?

  • The octane number of this fuel is very high.

  • A higher octane number in gasoline can lead to better engine performance.

  • The octane number indicates how well the fuel can resist knocking in an engine.

  • Using fuel with a low octane number can cause engine knocking and decrease efficiency.

Synonyms

octane rating
vsoctane number
  • Specialized
1 4.6

A number that shows how well car fuel stops the knocking sound in an engine

is a numerical measure on a standard scale quantifying resistance to knocking

How Resistant

high-octane
  • Specialized
1 6.8
octane number
  • Specialized
6.4

Surface Forms

octane number singular
octane numbers plural

Morphology

octane + number

The compound is compositionally regular: a B1 learner who knows 'octane' and 'number' can infer it denotes a numerical value associated with octane (i.e., a number relating to fuel quality). However, the precise technical meaning — that it measures resistance to engine knocking — requires specific domain knowledge, so the full sense is not completely predictable from the parts alone.

Etymology

Octane number comes from the name octane, a fuel chemical used in early fuel tests. People measured how much a fuel resisted 'knocking' in engines by comparing it to octane and gave the result as a 'number', so the term now means the figure that shows how well a fuel avoids engine 'knock'.