Butternut

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