The Collaborative International Dictionary of English v.0.48:

Souari nut \Sou*a"ri nut`\ (Bot.)
   The large edible nutlike seed of a tall tropical American
   tree (Caryocar nuciferum) of the same natural order with
   the tea plant; -- also called butternut. [Written also
   sawarra nut.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Butternut \But"ter*nut`\, n.
   1. (Bot.) An American tree (Juglans cinerea) of the Walnut
      family, and its edible fruit; -- so called from the oil
      contained in the latter. Sometimes called oil nut and
      white walnut.
      [1913 Webster]

   2. (Bot.) The nut of the Caryocar butyrosum and Caryocar
      nuciferum, of S. America; -- called also Souari nut.
      [1913 Webster]

WordNet (r) 3.0 (2006):

butternut
    n 1: North American walnut tree having light-brown wood and
         edible nuts; source of a light-brown dye [syn: butternut,
         butternut tree, white walnut, Juglans cinerea]
    2: oily egg-shaped nut of an American tree of the walnut family

U.S. Gazetteer Places (2000):

Butternut, WI -- U.S. village in Wisconsin
   Population (2000):    407
   Housing Units (2000): 220
   Land area (2000):     1.600841 sq. miles (4.146160 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    1.600841 sq. miles (4.146160 sq. km)
   FIPS code:            11525
   Located within:       Wisconsin (WI), FIPS 55
   Location:             46.013958 N, 90.494614 W
   ZIP Codes (1990):     54514
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Butternut, WI
    Butternut