\Le*nard" rays\ (Physics.)
Rays emanating from the outer surface of a plate composed of
any material permeable by cathode rays, as aluminium, which
forms a portion of a wall of a vacuum tube, or which is
mounted within the tube and exposed to radiation from the
cathode. Lenard rays are similar in all their known
properties to cathode rays. So called from the German
physicist Philipp Lenard (b. 1862), who first described them.