Source : Webster's Revised Unabridged Dictionary (1913)

Caper \Ca"per\, n. [F. c[^a]pre, fr. L. capparis, Gr. ?; cf. Ar.
   & Per. al-kabar.]
   1. The pungent grayish green flower bud of the European and
      Oriental caper ({Capparis spinosa}), much used for
      pickles.

   2. (Bot.) A plant of the genus {Capparis}; -- called also
      {caper bush}, {caper tree}.

   Note: The {Capparis spinosa} is a low prickly shrub of the
         Mediterranean coasts, with trailing branches and
         brilliant flowers; -- cultivated in the south of Europe
         for its buds. The {C. sodada} is an almost leafless
         spiny shrub of central Africa (Soudan), Arabia, and
         southern India, with edible berries.

   {Bean caper}. See {Bran caper}, in the {Vocabulary}.

   {Caper sauce}, a kind of sauce or catchup made of capers.

Source : WordNet®

caper sauce
     n : allemande sauce with capers