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}.
{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.]