Source : Webster's Revised Unabridged Dictionary (1913)

Sarsaparilla \Sar`sa*pa*ril"la\, n. [Sp. zarzaparrilla; zarza a
   bramble (perhaps fr. Bisc. zartzia) + parra a vine, or
   Parillo, a physician said to have discovered it.] (Bot.)
   (a) Any plant of several tropical American species of
       {Smilax}.
   (b) The bitter mucilaginous roots of such plants, used in
       medicine and in sirups for soda, etc.

   Note: The name is also applied to many other plants and their
         roots, especially to the {Aralia nudicaulis}, the wild
         sarsaparilla of the United States.

Source : WordNet®

sarsaparilla
     n 1: any of various prickly climbing plants of the tropical
          American genus Smilax having aromatic roots and
          heart-shaped leaves
     2: carbonated drink flavored with an extract from sarsaparilla
        root or with birch oil and sassafras