petrol /ˈpɛt.ɹəl/noun 2verb 1forms 5 noun2 •(Commonwealth) A fluid consisting of a mixture of refined petroleum hydrocarbons, primarily consisting of octane, commonly used as a motor fuel.We were the first company to introduce unleaded petrol in Britain, opening our first pump in June 1986. — 1987 •(informal) A motor vehicle powered by petrol (as opposed to diesel). verb1 •(old-fashioned) To fill or supply (a vehicle, etc.) with petrol. formspetroled · petrolled · petroling · petrolling · petrols