- A mixture of liquid hydrocarbons found in the earth in various parts of the world and believed to be derived from fossilized animal and plant remains; the source of petrolatum, in addition to its use for lighting and heating purposes. SYN: coal oil, rock oil. [L. petra, rock, + oleum, oil]- p. benzin purified, low boiling fractions distilled from p. consisting of hydrocarbons, chiefly of the methane series; it is highly flammable, and its vapors, when mixed with air and ignited, may explode; used as a solvent. SYN: benzin, benzine, naphtha, p. ether.
* * *pe·tro·leum pə-'trō-lē-əm, -'trōl-yəm n 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
* * *pe·tro·le·um (pə-troґle-əm) [L. petra stone + oleum] a thick natural mixture of solid, liquid, and gaseous hydrocarbons obtained from beneath the surface of the earth. It consists mainly of a mixture of various alkanes, cycloalkanes, and aromatic hydrocarbons as well as small amounts of sulfur, nitrogen, and oxygen compounds.
Medical dictionary. 2011.