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]

The Free On-line Dictionary of Computing (17 December 2009):

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.


U.S. Gazetteer (1990):

Seneca, IL (village, FIPS 68640)
  Location: 41.30337 N, 88.61352 W
  Population (1990): 1878 (685 housing units)
  Area: 7.7 sq km (land), 0.2 sq km (water)
  Zip code(s): 61360
Seneca, KS (city, FIPS 63950)
  Location: 39.83570 N, 96.06578 W
  Population (1990): 2027 (944 housing units)
  Area: 3.2 sq km (land), 0.0 sq km (water)
Seneca, MO (city, FIPS 66674)
  Location: 36.83788 N, 94.60849 W
  Population (1990): 1885 (831 housing units)
  Area: 4.5 sq km (land), 0.0 sq km (water)
  Zip code(s): 64865
Seneca, NE (village, FIPS 44385)
  Location: 42.04272 N, 100.83134 W
  Population (1990): 78 (44 housing units)
  Area: 0.3 sq km (land), 0.0 sq km (water)
  Zip code(s): 69161
Seneca, NM
  Zip code(s): 88437
Seneca, OR (city, FIPS 66200)
  Location: 44.13470 N, 118.97564 W
  Population (1990): 191 (121 housing units)
  Area: 2.2 sq km (land), 0.0 sq km (water)
  Zip code(s): 97873
Seneca, PA (CDP, FIPS 69272)
  Location: 41.37574 N, 79.70553 W
  Population (1990): 1029 (423 housing units)
  Area: 5.8 sq km (land), 0.0 sq km (water)
  Zip code(s): 16346
Seneca, SC (town, FIPS 65095)
  Location: 34.68613 N, 82.95782 W
  Population (1990): 7726 (3367 housing units)
  Area: 16.4 sq km (land), 0.1 sq km (water)
  Zip code(s): 29678
Seneca, SD (town, FIPS 58180)
  Location: 45.06097 N, 99.50808 W
  Population (1990): 81 (45 housing units)
  Area: 1.1 sq km (land), 0.0 sq km (water)
  Zip code(s): 57473