The Collaborative International Dictionary of English v.0.48:

Coumaric \Cou*mar"ic\ (k??-m?r"?k), a.
   Relating to, derived from, or like, the Dipterix odorata, a
   tree of Guiana.
   [1913 Webster]

   Coumaric acid (Chem.), one of a series of aromatic acids,
      related to cinnamic acid, the most important of which is a
      white crystalline substance, HO.C6H4.C2H2.CO2H, obtained
      from the tonka bean, sweet clover, etc., and also produced
      artificially.
      [1913 Webster]