PETROLEUM

[pe.tro.leum] n [ME, fr. ML, fr. L petr- + oleum oil--more at oil] (15c): an oily flammable bituminous liquid that may vary from almost colorless to black, occurs in many places in the upper strata of the earth, is a complex mixture of hydrocarbons with small amounts of other substances, and is prepared for use as gasoline, naphtha, or other products by various refining processes