rest mass
Noun
Meaning
(physics) the mass of a body as measured when the body is at rest relative to an observer, an inherent property of the body
Source: WordNetHypernyms
Examples
Although solar wind particles have rest mass and photons do not, sunlight has thousands of times more momentum than the solar wind.
An electron at the far right of the curve would have the maximum possible kinetic energy, leaving the energy of the neutrino to be only its small rest mass.
De Broglie's formula was confirmed three years later for electrons (which differ from photons in having a rest mass ) with the observation of electron diffraction in two independent experiments.
For example, the total mass-energy content of the neutral pion is converted into gammas, not just its rest mass.
In order to formulate the equations of physics such that mass values do not change between observers, it is convenient to use rest mass.
Neutrinos oscillate in three flavors and all neutrinos have their rest mass.