Noun
avgas (countable and uncountable, plural avgases or avgasses)
(aviation) Gasoline fuel for piston-engined aircraft.
By the time of Operation Overlord during World War II both the RAF and USAAF were conducting some operations in Europe using 150 RON fuel (100/150 avgas ), obtained by adding 2.5% aniline to 100 octane avgas. Source: Internet
Turboprop-powered aircraft have become popular for bush airplanes such as the Cessna Caravan and Quest Kodiak as jet fuel is easier to obtain in remote areas than is aviation-grade gasoline ( avgas ). Source: Internet