A '''barrel''' is a unit of [[volume]] that equals 42 U.S. [[gallon]]s of liquid at 60° [[Fahrenheit]].<ref>U.S. Department of Transportation Maritime Administration [http://www.marad.dot.gov/publications/glossary/glossary.html]</ref>
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A '''barrel''' is a unit of [[volume]] that equals 42 U.S. [[gallon]]s of liquid at 60° [[Fahrenheit]].<ref>U.S. Department of Transportation Maritime Administration [http://www.marad.dot.gov/publications/glossary/glossary.html]</ref> A common use of the term barrel is in regard to oil, where prices and quantities are usually referred to by the barrel.