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 (J. 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, or European, walnut, a tree (J. 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 (J. cinerea), bearing long, oval, thick-shelled, oily nuts, commonly called butternuts. See Butternut., European Eu`ro*pe"an, a. [L. europeaus, Gr. ?, fr. Gr. ? (L. europa.)] Of or pertaining to Europe, or to its inhabitants. On the European plan, having rooms to let, and leaving it optional with guests whether they will take meals in the house; -- said of hotels. [U. S.], European Eu`ro*pe"an, n. A native or an inhabitant of Europe.