An oxygenate is a type of chemical added to liquid fuels like gasoline. They contain oxygen, and help make the fuel burn completely. This reduces soot and smog produced by incomplete combustion. Most oxygenates are alcohols or ethers. Gasoline with added oxygenates is sometimes called reformulated gasoline or oxygenated gasoline.
Important oxygenates include ethanol and ethyl tert-butyl ether.