The Collaborative International Dictionary of English v.0.48:

Succedaneous \Suc`ce*da"ne*ous\, a. [L. succedaneus. See
   Succeed.]
   Pertaining to, or acting as, a succedaneum; supplying the
   place of something else; being, or employed as, a substitute
   for another. --Sir T. Browne.
   [1913 Webster]