The Collaborative International Dictionary of English v.0.48:

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]

WordNet (r) 3.0 (2006):

Seneca
    n 1: Roman statesman and philosopher who was an advisor to Nero;
         his nine extant tragedies are modeled on Greek tragedies
         (circa 4 BC - 65 AD) [syn: Seneca, Lucius Annaeus
         Seneca]
    2: a member of the Iroquoian people formerly living in New York
       State south of Lake Ontario
    3: the Iroquoian language spoken by the Seneca

The Free On-line Dictionary of Computing (19 January 2023):

Oberon-V
Seneca

   (Formerly Seneca).  R. Griesemer, 1990.  Descendant of Oberon
   designed for numerical applications on supercomputers,
   especially vector or pipelined architectures.  Includes array
   constructors and an ALL statement.  "Seneca - A Language for
   Numerical Applications on Vectorcomputers", Proc CONPAR 90 -
   VAPP IV Conf.  R. Griesemer, Diss Nr. 10277, ETH Zurich.