An Etymological Dictionary of Astronomy and Astrophysics

1. The energy in the form of heat emitted by an object by virtue of its temperature.
   

2. The total potential and kinetic energies associated with the random motions of the particles of a material. The quantity of thermal energy possessed by a body determines
   its temperature. The thermal energy which is absorbed, given up, or transferred from one material to another is heat.
   

3. The characteristic energy of → thermal neutrons at room temperature, about 0.025 eV.

See also: → thermal; → energy.