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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

One joule is not a large amount of energy; it would lift a small 100-gram apple a distance of about 1 meter.

From Textbooks ● Aug. 12, 2015

They had discovered the X ray, the cathode ray, the electron, and radioactivity, invented the ohm, the watt, the Kelvin, the joule, the amp, and the little erg.

From "A Short History of Nearly Everything" by Bill Bryson

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

This new research, published today in the journal Joule, looked at ways this could be achieved for industry.

From Science Daily ● Jan. 31, 2024

Dr. Joule attached a fixed weight to a string which was passed over a pulley, while the other end was connected with paddles moving in water.

From Joseph Smith as Scientist A Contribution to Mormon Philosophy by Widtsoe, John Andreas

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

Firstly, you've probably heard of the units of measurement for energy — calories — as well as the metric equivalent, which is joules.

From Salon ● Aug. 24, 2023

While the laser energy of 2 million joules was less than the fusion yield of 3 million joules, it took the facility nearly 300 million joules to produce the lasers used in this experiment.

From Salon ● Jan. 2, 2023

The energy is in joules for a charge in coulombs, voltage in volts, and capacitance in farads.

From Textbooks ● Aug. 12, 2015

In a pure-oxygen environment, 16.7 million joules will be released for every kilogram of sugar used, releasing the explosive force of eight sticks of dynamite.

From "The Martian" by Andy Weir