noun
: the energy that is needed for a particle to come from the interior of a medium and break through the surface — used especially of the photoelectric and thermionic emission of electrons from metals
noun
: the energy that is needed for a particle to come from the interior of a medium and break through the surface — used especially of the photoelectric and thermionic emission of electrons from metals
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012