Wal·nut n.  Bot. The fruit or nut of any tree of the genus Juglans; also, the tree, and its timber. The seven or eight known species are all natives of the north temperate zone.
  Note: ☞ In some parts of America, especially in New England, the name walnut is given to several species of hickory (Carya), and their fruit.
  Ash-leaved walnut, a tree (Juglans fraxinifolia), native in Transcaucasia.
  Black walnut, a North American tree (Juglans nigra) valuable for its purplish brown wood, which is extensively used in cabinetwork and for gunstocks.  The nuts are thick-shelled, and nearly globular.
  English walnut, or European walnut, a tree (Juglans regia), native of Asia from the Caucasus to Japan, valuable for its timber and for its excellent nuts, which are also called Madeira nuts.
  Walnut brown, a deep warm brown color, like that of the heartwood of the black walnut.
  Walnut oil, oil extracted from walnut meats.  It is used in cooking, making soap, etc.
  White walnut, a North American tree (Juglans cinerea), bearing long, oval, thick-shelled, oily nuts, commonly called butternuts.  See Butternut.
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  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.
  2. Bot. The nut of the Caryocar butyrosum and Caryocar nuciferum, of S. America; -- called also Souari nut.
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  Juglans cinerea
       n : North American walnut tree having light-brown wood and
           edible nuts; source of a light-brown dye [syn: butternut,
            butternut tree, white walnut]