The Collaborative International Dictionary of English v.0.48:

Phosphorescence \Phos`phor*es"cence\, n. [Cf. F.
   phosphorescence.]
   1. The quality or state of being phosphorescent.
      [1913 Webster]

   2. The process of phosphorescing, especially that of emitting
      light after a source of excitation has been removed. This
      contrasts with the process of fluorescence, in which a
      substance emits light of a lower wavelength than the
      illuminating light, only while the illumination continues.
      [PJC]

   3. Light emitted by the process of phosphorescence.
      [1913 Webster]

WordNet (r) 3.0 (2006):

phosphorescence
    n 1: a fluorescence that persists after the bombarding radiation
         has ceased

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "phosphorescence":
   autoluminescence, bioluminescence, cathode luminescence,
   chemicoluminescence, chemiluminescence, corposant,
   crystalloluminescence, double corposant, electroluminescence,
   fata morgana, fluorescence, fox fire, ignis fatuus, luciferase,
   luciferin, luminescence, luminophor, marshfire, noctiluscence,
   phosphor, photoluminescence, radioluminescence, thermoluminescence,
   tribofluorescence, triboluminescence, tribophosphorescence, wisp,
   witch fire