Source : Webster's Revised Unabridged Dictionary (1913)

Decadence \De*ca"dence\, Decadency \De*ca"den*cy\, n. [LL.
   decadentia; L. de- + cadere to fall: cf. F. d['e]cadence. See
   {Decay}.]
   A falling away; decay; deterioration; declension. ``The old
   castle, where the family lived in their decadence.'' --Sir W.
   Scott.

Source : WordNet®

decadency
     n : the state of being degenerate in mental or moral qualities
         [syn: {degeneracy}, {degeneration}, {decadence}]