The Collaborative International Dictionary of English v.0.48:

goldenseal \goldenseal\ n.
   A perennial herb of Northeastern U. S. (Hydrastis
   Canadensis) having a thick knotted yellow rootstock and
   large rounded leaves.

   Syn: golden seal, yellow root, turmeric root, Hydrastis
        Canadensis.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

goldenseal
    n 1: perennial herb of northeastern United States having a thick
         knotted yellow rootstock and large rounded leaves [syn:
         goldenseal, golden seal, yellow root, turmeric
         root, Hydrastis Canadensis]