The DICT Development Group

  Senecas \Sen"e*cas\, n. pl.; sing. Seneca. (Ethnol.)
     A tribe of Indians who formerly inhabited a part of Western
     New York. This tribe was the most numerous and most warlike
     of the Five Nations.
     [1913 Webster]
  
     Seneca grass(Bot.), holy grass. See under Holy.
  
     Seneca eil, petroleum or naphtha.
  
     Seneca root, or Seneca snakeroot (Bot.), the rootstock of
        an American species of milkworth ({Polygala Senega)
        having an aromatic but bitter taste. It is often used
        medicinally as an expectorant and diuretic, and, in large
        doses, as an emetic and cathartic. [Written also Senega
        root, and Seneka root.]
        [1913 Webster]

  Seneca snakeroot
      n 1: eastern North American plant having a terminal cluster of
           small white flowers and medicinal roots [syn: Seneca
           snakeroot, Seneka snakeroot, senga root, senega
           root, senega snakeroot, Polygala senega]