internal energy

American  

noun

Thermodynamics.

1. a function of thermodynamic variables, as temperature, that represents the internal state of a system that is due to the energies of the molecular constituents of the system. The change in internal energy during a process is equal to the net heat entering the system minus the net work done by the system. U

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internal energy British  

noun

1. U, E. the thermodynamic property of a system that changes by an amount equal to the work done on the system when it suffers an adiabatic change. It is the sum of the kinetic and potential energies of its constituent atoms, molecules, etc

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Etymology

Origin of internal energy

First recorded in 1885–90

Compare meaning

How does internal-energy compare to similar and commonly confused words? Explore the most common comparisons:

• enthalpy vs. internal energy

Example Sentences

See Examples For:

internal energy

It will also enhance supply security and meet internal energy needs as well as broader European gas demand amid the continuing regional energy uncertainty.

From The Wall Street Journal ● Sep. 14, 2026

Researchers also learned that sperm draw on internal energy reserves they already carry when their journey begins.

From Science Daily ● Feb. 14, 2026

A metal that could produce its own internal energy at first seemed like a violation of the laws of physics.

From Salon ● Aug. 12, 2023

It can’t; it has too much internal energy and direction for any single misstep, including Hansberry’s, to throw the whole thing off track.

From New York Times ● Oct. 25, 2022

Mayer obtained a result equivalent to 36.5 × 106 ergs per calorie. 105The assumption on which this calculation is founded is that there is no alteration of the internal energy of the gas in consequence of expansion.

From Lord Kelvin An account of his scientific life and work by Andrew Gray