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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.

• joules
  plural

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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Other Word Forms

Noun Inflected Forms

• joules
  plural

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

See Examples For:

joule Joule joules

Using exciton-polaritons, the Penn researchers demonstrated all-light switching while using only about 4 quadrillionths of a joule of energy.

From Science Daily ● May 19, 2026

However, in an interesting twist, scientists also found that cooking with a smaller flame produced more benzene per joule of gas consumed.

From Los Angeles Times ● Jun. 21, 2023

Its value depends on ambient temperature: in your living room, one Landauer would be around 10–21 joule.

From Scientific American ● Mar. 29, 2022

The SI unit of heat, work, and energy is the joule.

From Textbooks ● Feb. 14, 2019

They had already covered their lightweight chaulnots with their heavy woolen ones against the coming evening chill—proof that not one joule of energy had been converted to heat by means of respectable labor.

From "Strange the Dreamer" by Laini Taylor

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

A new study from Meng's group, published in Joule, takes a major step toward solving that issue.

From Science Daily ● Oct. 17, 2025

The present condition of the molecular theory of gases, and of molecular science generally, is due almost entirely to the work of Joule, Clausius, Boltzmann, and Maxwell.

From Heroes of Science: Physicists by William Garnett

This drug can create a deep state of anesthesia and amnesia sufficient to block the pain of a surgeon’s knife or 400 joules of electricity delivered to reset a fibrillating heart.

From Slate ● Aug. 20, 2024

When the U.S. government completed construction of the National Ignition Facility in 2009, it was the most powerful laser facility in the world, able to deliver 1 million joules of energy to a target.

From Salon ● Jan. 2, 2023

The 2 million joules it produces today is 50 times more energetic than the next most powerful laser on Earth.

From Salon ● Jan. 2, 2023

The energy is in joules when the charge is in coulombs, voltage is in volts, and capacitance is in farads.

From Textbooks ● Aug. 12, 2015

The sky shook with endless thunder and erupted with lightning, the clouds bursting with a billion joules of energy.

From "City of the Plague God" by Sarwat Chadda