an oily, flammable, liquid solution of hydrocarbons, yellowish-green to black in color, occurring naturally in the rock strata of certain geological formations: when fractionally distilled, it yields paraffin, fuel oil, kerosene, gasoline, etc.
See petroleum in American Heritage Dictionary 4
(pə-trōˈlē-əm)
noun
A thick, flammable, yellow-to-black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the earth's surface, can be separated into fractions including natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, and asphalt and is used as raw material for a wide variety of derivative products.