Definition of rest mass in English:

rest mass


  • The mass of a body when at rest.

    ‘The concept of the rest mass derives from special relativity.’
    • ‘The neutrino was known from the start to be an extraordinarily light particle, perhaps massless, since its rest mass could never be detected.’
    • ‘Any object with a non-zero rest mass (like a dust mote) can never reach light speed.’
    • ‘A photon has zero rest mass, but it carries energy and momentum.’
    • ‘Wolfgang Pauli suggested in 1930 that beta decay must involve a third particle that would be neutral, have negligible rest mass and a spin of one-half.’