Source : Webster's Revised Unabridged Dictionary (1913)

Phosphorescence \Phos`phor*es"cence\, n. [Cf. F.
   phosphorescence.]
   1. The quality or state of being phosphorescent; or the act
      of phosphorescing.

   2. A phosphoric light.

Source : WordNet®

phosphorescence
     n : a fluorescence that persists after the bombarding radiation
         has ceased