An Etymological Dictionary of Astronomy and Astrophysics

The condition of a → thermodynamic system in which the available → energy is distributed uniformly among all the possible forms of energy. Furthermore,
all → thermodynamic process es must be exactly balanced by their reverse processes. For example, inside a star there will be as many → ionizations of helium per second as there are → recombinations of free electrons and helium ions. Se also
→ local thermodynamic equilibrium (LTE).

See also: → thermodynamic; → equilibrium.