(Science: botany) 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.
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 colour, 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.
Origin: OE. Walnot, AS. Wealh-hnutu a Welsh or foreign nut, a walnut; wealh foreign, strange, n, a Welshman, Celt (akin to OHG. Walh, properly, a Celt, from the name of a Celtic tribe, in L. Volcae) – hnutu a nut; akin to D. Walnoot, G. Walnuss, Icel. Valhnot, Sw. Valnot, Dan valnod. See Nut, and cf. Welsh.