Source : Webster's Revised Unabridged Dictionary (1913)

Radiance \Ra"di*ance\, Radiancy \Ra"di*an*cy\, n.
   The quality of being radiant; brilliancy; effulgence; vivid
   brightness; as, the radiance of the sun.

         Girt with omnipotence, with radiance crowned. --Milton.

         What radiancy of glory, What light beyond compare !
                                                  --Neale.

   Syn: Luster; brilliancy; splendor; glare; glitter.

Source : WordNet®

radiance
     n 1: the amount of electromagnetic radiation leaving or arriving
          at a point on a surface [syn: {glow}, {glowing}]
     2: the quality of being bright and sending out rays of light
        [syn: {radiancy}, {shine}, {effulgence}, {refulgence}, {refulgency}]
     3: an attractive combination of good health and happiness; "the
        radiance of her countenance"