Plain English Meaning

A number on the fuel that tells you how well it resists exploding the wrong way inside the engine. Higher number means the fuel can handle more pressure and heat before it misbehaves.

Full Definition

A rating that indicates a fuel's resistance to detonation (uncontrolled combustion) inside a piston engine. In aviation gasoline (avgas), the octane rating tells the pilot which fuel grade is approved for the engine; using a lower-rated fuel than specified can cause the fuel-air mixture to ignite prematurely or explode rather than burn smoothly, damaging the engine.

Context Anchor

Pilots encounter octane when selecting or checking aviation gasoline for a -engine .