hazelnut . ( Of the lat. )( abellana [nux] , of Abella , Avella, town in Campania). 1. f. fruit of the hazelnut. It is nearly spherical, about two inches in diameter, with thin, hard crust and color of cinnamon, within which, and covered with a reddish film, there is a pleasant taste, oily and white meat. 2. f. mineral coal in the basin of Puertollano, in the province of city Royal, Spain, washed and graded, whose pieces must have a regulatory size between 15 and 25 mm. hazelnut of the India, or hazelnut Indica. 1. f. mirobálano.