Octane \Oc"tane\, n. [See {Octa-}] . (Chem.) Any one of a group of metametric hydrocarcons ({C8H18}) of the methane series. The most important is a colorless, volatile, inflammable liquid, found in petroleum, and a constituent of benzene or ligroin. Dibutyl \Di*bu"tyl\, n. [Pref. di- + butyl.] (Chem.) A liquid hydrocarbon, {C8H18}, of the marsh-gas series, being one of several octanes, and consisting of two butyl radicals. Cf. {Octane}.