A nut is the hard edible kernel of any of several species, including walnuts, Brazil nuts, cashews, almonds and the like. The default will differ from place to place. In France, Spain and Italy the defauls is walnuts, so assume walnuts unless otherwise informed. When I was a child, nuts meant the hazel nuts which grew on the bushes and small trees all over the village, following on from the catkins of spring. Some things which are not actually nuts are called by the name, so that a pulse, the peanut (US: ground nut) is one of the best known ‘nuts’.