Definition of mass energy in US English:

mass energy

noun

Physics
  • 1Mass and energy regarded as interconvertible manifestations of the same phenomenon, according to the laws of relativity.

    • ‘Thus, they must have a rest mass energy roughly equal to the unification energy.’
    • ‘In the special theory of relativity Einstein demonstrated that neither mass nor energy were conserved separately, but that they could be traded one for the other and only the total mass energy was conserved.’
    • ‘Back then, radioactivity had recently been discovered and mass energy conservation was under assault because of its discovery.’
    1. 1.1 The mass of a body regarded relativistically as energy.
      • ‘The famous Einstein relationship for energy includes both the kinetic energy and rest mass energy for a particle.’
      • ‘The energy of our photon is thus 3. 55x10-19 J. Note that this is 35 or so orders of magnitude below mass energy.’
      • ‘The answer lies in the fact that mass energy is somewhat like potential energy, in that it is only apparent or useful to us if it is converted into another form of energy, like kinetic energy.’

Pronunciation

mass energy

/mas ˈenərjē/