electron-volt \electron-volt\ n.
   a unit of energy, being equal to the kinetic energy acquired
   by an electron when accelerated through a potential
   difference of one volt. It is equal to 1.602 x 10^-19
   Joules. It is abbreviated eV.

   Note: The unit electron-volt is often used to express the
         rest mass and the energy of fundamental particles,
         especially when accelerated to high velocity in an
         accelerator. In accelerators, the units encountered are
         more commonly megaelectron-volts (MeV or million
         electron-volts) and giga-electron-volts (GeV or billion
         electron-volts).
         [PJC]