petroleum

from The American Heritage® Dictionary of the English Language, 5th Edition.

• 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.

from The Century Dictionary.

• noun An oily substance of great economical importance, especially as a source of light, occurring naturally oozing from crevices in rocks, or floating on the surface of water, and also obtained in very large quantity in various parts of the world by boring into the rock; rock-oil.
• noun Of the entire product of petroleum throughout the world approximately 50 per cent. is furnished by Russia, 40 per cent, by the United States, and 10 per cent. by Canada, Austria, Rumania, the Sunda Islands, Burmah, Japan, and (in quite small proportion) Germany, South America, and Italy. California, Texas, and Kansas have of late largely increased their output, chiefly of crude fuel-oil, while in Pennsylvania, Ohio, and West Virginia there has been a diminished yield. It should be noted that American and Russian petroleum differ materially in chemical composition, the former consisting mainly of hydrocarbons of the paraffin series, while the latter represent chiefly naphthenes, isomeric but not identical with the members of the olefine series.

from the GNU version of the Collaborative International Dictionary of English.

• noun Rock oil, mineral oil, or natural oil, a dark brown or greenish inflammable liquid, which, at certain points, exists in the upper strata of the earth, from whence it is pumped, or forced by pressure of the gas attending it. It consists of a complex mixture of various hydrocarbons, largely of the methane series, but may vary much in appearance, composition, and properties. It is refined by distillation, and the products include kerosene, benzine, gasoline, paraffin, etc.
• noun a volatile liquid obtained in the distillation of crude petroleum at a temperature of 170° Fahr., or below. The term is rather loosely applied to a considerable range of products, including benzine and ligroin. The terms petroleum ether, and naphtha, are sometimes applied to the still more volatile products, including rhigolene, gasoline, cymogene, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A flammable liquid ranging in color from clear to very dark brown and black, consisting mainly of hydrocarbons, occurring naturally in deposits under earth surface.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a dark oil consisting mainly of hydrocarbons