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• joule
  joule

  noun

  the standard unit of work or energy in the International System of Units (SI), equal to the work done by a force of one newton when its point of application moves through a distance of one meter in the direction of the force: equivalent to 10 7 ergs and one watt-second. J, j
• Joule
  Joule

  noun

  James Prescott, 1818–89, English physicist.

joule

¹ American  

[jool, joul] / dʒul, dʒaʊl /

noun

Physics.

1. the standard unit of work or energy in the International System of Units (SI), equal to the work done by a force of one newton when its point of application moves through a distance of one meter in the direction of the force: equivalent to 10 7 ergs and one watt-second. J, j

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Joule ² American  

[jool, joul] / dʒul, dʒaʊl /

noun

1. James Prescott, 1818–89, English physicist.

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Joule ¹ British  

/ dʒuːl /

noun

1. James Prescott. 1818–89, English physicist, who evaluated the mechanical equivalent of heat and contributed to the study of heat and electricity

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joule ² British  

/ dʒuːl /

noun

1.  J.  the derived SI unit of work or energy; the work done when the point of application of a force of 1 newton is displaced through a distance of 1 metre in the direction of the force. 1 joule is equivalent to 1 watt-second, 10 ⁷ ergs, 0.2390 calories, or 0.738 foot-pound

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Joule ¹ Scientific  

1. British physicist who demonstrated that heat is a form of energy. His work established the law of conservation of energy, stating that energy is never destroyed but may be converted from one form into another. The joule unit of energy is named for him.

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joule ² Scientific  

/ jo̅o̅l,joul /

1. The SI derived unit used to measure energy or work. One joule is equal to the energy used to accelerate a body with a mass of one kilogram using one newton of force over a distance of one meter. One joule is also equivalent to one watt-second.

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Etymology

Origin of joule

First recorded in 1885–90; named after J. P. Joule

Explanation

Use the scientific term joule for talking about work, energy, or heat. One joule is equal to the work it takes to make a watt of power for a second, or to move a body one meter with a one-Newton force. In physics, it's common to talk about joules of energy — one example used to illustrate a joule is lifting an apple, which weighs about one Newton. If you raise the apple one meter in the air, you've used one joule of work. The word joule comes from the English physicist James Prescott Joule, who studied the relationship between heat and mechanical work, research that led to the First Law of Thermodynamics.

Example Sentences

He enjoyed biking and had a dog named Joule.

From Slate • Jan. 26, 2026

Pretti loved adventures with his beloved Catahoula Leopard dog Joule, who died around a year ago, AP reported.

From BBC • Jan. 25, 2026

For the Joule project, he said, “we’ve brought on 30 people to date and are looking for more.”

From The Wall Street Journal • Dec. 30, 2025

Rachel Yang, chef and co-owner of the critically acclaimed Seattle restaurants Revel and Joule, reveals her sweet side with her passion project Paper Cake Shop in Wallingford.

From Seattle Times • Nov. 24, 2023

The assumption which Mayer made was shown experimentally by Joule to be nearly correct.

From Heroes of Science: Physicists by Garnett, William