Source : Webster's Revised Unabridged Dictionary (1913)

Decedent \De*ce"dent\, a. [L. decedens, p. pr. of decedere.]
   Removing; departing. --Ash.

Decedent \De*ce"dent\, n.
   A deceased person. --Bouvier.

Source : WordNet®

decedent
     n : someone who is no longer alive; "I wonder what the dead
         person would have done" [syn: {dead person}, {dead soul},
          {deceased person}, {deceased}, {departed}]