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[puh-troh-lee-uh m] /pəˈtroʊ li əm/
an oily, thick, flammable, usually dark-colored liquid that is a form of bitumen or a mixture of various hydrocarbons, occurring naturally in various parts of the world and commonly obtained by drilling: used in a natural or refined state as fuel, or separated by distillation into gasoline, naphtha, benzene, kerosene, paraffin, etc.
Origin of petroleum
1520-30; < Medieval Latin: literally, rock oil, equivalent to Latin petr(a) rock (< Greek pétra) + oleum oil
Related forms
petroleous, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for petroleum
Contemporary Examples
Historical Examples
  • It also chanced that this whole country abounded in signs of petroleum.

    Memoirs Charles Godfrey Leland
  • It has a grade of petroleum that differs from any other thus far found in the world.

    Checking the Waste Mary Huston Gregory
  • This petroleum also contains asphalt and other chemical products.

    Checking the Waste Mary Huston Gregory
  • Kerosene oil is only one of the many substances found in petroleum.

    Diggers in the Earth Eva March Tappan
  • petroleum is a mixture of various compounds known as hydrocarbons.

    Commercial Geography

    Jacques W. Redway
British Dictionary definitions for petroleum


a dark-coloured thick flammable crude oil occurring in sedimentary rocks around the Persian Gulf, in parts of North and South America, and below the North Sea, consisting mainly of hydrocarbons. Fractional distillation separates the crude oil into petrol, paraffin, diesel oil, lubricating oil, etc. Fuel oil, paraffin wax, asphalt, and carbon black are extracted from the residue
Word Origin
C16: from Medieval Latin, from Latin petra stone + oleum oil
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for petroleum

early 15c. "petroleum, rock oil" (mid-14c. in Anglo-French), from Medieval Latin petroleum, from Latin petra "rock" (see petrous) + oleum "oil" (see oil (n.)).

Online Etymology Dictionary, © 2010 Douglas Harper
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petroleum in Science
A thick, flammable, yellow-to-black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the Earth's surface. It can be separated into fractions including natural gas, gasoline, naphtha, kerosene, paraffin wax, asphalt, and fuel and lubricating oils, and is used as raw material for a wide variety of derivative products. It is believed to originate from the accumulated remains of fossil plants and animals, especially in shallow marine environments.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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