thermodynamics

American  

[thur-moh-dahy-nam-iks] / ˌθɜr moʊ daɪˈnæm ɪks /

noun

(used with a singular verb)

1. the science concerned with the relations between heat and mechanical energy or work, and the conversion of one into the other: modern thermodynamics deals with the properties of systems for the description of which temperature is a necessary coordinate.

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thermodynamics British  

/ ˌθɜːməʊdaɪˈnæmɪks /

noun

1. (functioning as singular) the branch of physical science concerned with the interrelationship and interconversion of different forms of energy and the behaviour of macroscopic systems in terms of certain basic quantities, such as pressure, temperature, etc See also law of thermodynamics

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thermodynamics Scientific  

/ thûr′mō-dī-năm′ĭks /

1. The branch of physics that deals with the relationships between heat and other forms of energy. Four basic laws have been established.

2. ◆ The first law states that the amount of energy added to a system is equal to the sum of its increase in heat energy and the work done on the system. The first law is an example of the principle of conservation of energy.

3. ◆ The second law states that heat energy cannot be transferred from a body at a lower temperature to a body with a higher one without the addition of energy. Thus, warm air outside can transfer its energy to a cold room, but transferring energy out of a cold room to the air outside requires extra energy (as with an air conditioner).

4. ◆ The third law states that the entropy of a pure crystal at absolute zero is zero. Since there can be no physical system with lower entropy, all entropy is thus defined to have a positive value.

5. ◆ The zeroth law states that if two bodies are in thermal equilibrium with some third body, then they are also in equilibrium with each other. This law has its name because it was implicitly assumed in the development of the other laws, and is in fact more fundamental than the others, but was only later established as a law itself.

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thermodynamics Cultural  

1. The branch of physics devoted to the study of heat and related phenomena. The behavior of heat is governed by the three laws of thermodynamics: (1) The total energy of an isolated system cannot change; this is the law of conservation of energy. (2) Heat will not flow from a cold to a hot object spontaneously (see entropy). (3) It is impossible, in a finite number of operations, to produce a temperature of absolute zero.

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Discover More

All thermodynamic properties of matter can be understood in terms of the motion of atoms and molecules.

Other Word Forms

• thermodynamicist noun

Etymology

Origin of thermodynamics

First recorded in 1850–55; thermo- + dynamics

Explanation

Thermodynamics is the study of energy, particularly heat energy. A physicist who's interested in the way temperature relates to energy and work might concentrate on thermodynamics. If you take a physics class, you'll come across the term thermodynamics. The study of heat energy and how it works originally focused on early steam engines, which powered trains in the 19th century. The word itself was coined in the mid-1800s and originally hyphenated, thermo-dynamics, from two Greek roots, therme, "heat," and dynamis, "power" or "energy."

Example Sentences

Quentin Gee, a manager at the California Energy Commission, said the advantage of heat pumps comes down to thermodynamics.

From Los Angeles Times • Mar. 1, 2026

"These results show why such an atomic cloud does not thermalize -- why it doesn't distribute its energy according to the usual laws of thermodynamics" says Møller.

From Science Daily • Jan. 7, 2026

Experiments like these laid the groundwork for thermodynamics in the 19th century.

From Science Daily • Dec. 23, 2025

Speaking at the event on Friday, Ramanna said his system was inspired by the first law of thermodynamics.

From The Wall Street Journal • Nov. 10, 2025

You probably expected a thousand words on gravity or the four laws of thermodynamics, not a journal recounting the last 144 days of my life—possibly of all life—interspersed with crazy doomsday scenarios.

From "We Are the Ants" by Shaun David Hutchinson