butternut

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An eastern North American walnut (Juglans cinerea) having light-brown wood, pinnately compound leaves, and a deeply furrowed nut enclosed in an egg-shaped, sticky, aromatic husk.
• noun The nut of this tree, having an edible sweet kernel.
• noun The wood of this tree, used for furniture, boxes, and interior finishes.
• noun The bark of this tree.
• noun A brownish dye obtained from the husks of the fruits of this tree.
• noun Clothing dyed with butternut extract, especially the uniforms of Confederate soldiers in the Civil War.
• noun Informal A Confederate soldier or partisan in the Civil War.

from The Century Dictionary.

• noun The fruit of Juglans cinerea, an American tree, so called from the oil it contains; also, the tree itself.
• noun The nut of Caryocar nuciferum, a lofty timber-tree of Guiana, natural order Ternstrœmaceæ.
• noun A name applied during the civil war in the United States to Confederate soldiers, in allusion to the coarse brown homespun cloth, dyed with butternut, often worn by them.

from the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A North American walnut tree, Juglans cinerea, or the wood, bark, or nut of this tree.
• noun A dye made from the fruit of this tree.
• noun informal Butternut squash

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun North American walnut tree having light-brown wood and edible nuts; source of a light-brown dye
• noun oily egg-shaped nut of an American tree of the walnut family