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

---

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

---

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

Liquid water combined with internal energy sources makes these moons compelling targets in the search for life.

From Science Daily • Mar. 1, 2026

The researchers think that the animals' use of internal energy, or active transport, when moving the salts could be the explanation.

From Science Daily • Oct. 6, 2023

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

Now a well-known relation connects the available energy of a reversible system with the corresponding change in its total internal energy.

From Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" by Various