Source : Webster's Revised Unabridged Dictionary (1913)

Succedaneum \Suc`ce*da"ne*um\, n.; pl. {Succedanea}. [NL. See
   {Succedaneous}.]
   One who, or that which, succeeds to the place of another;
   that which is used for something else; a substitute;
   specifically (Med.), a remedy used as a substitute for
   another.

         In lieu of me, you will have a very charming
         succedaneum, Lady Harriet Stanhope.      --Walpole.

Source : WordNet®

succedaneum
     n : (medicine) something that can be used as a substitute
         (especially any medicine that may be taken in place of
         another)
     [also: {succedanea} (pl)]

succedanea
     See {succedaneum}