Walnut 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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