1. (Science: botany) The fruit of the Corylus Avellana or hazel. It is an oval nut, containing a kernel that has a mild, farinaceous, oily taste, agreeable to the palate.
in England filberts are usually large hazelnuts, especially the nuts from selected and cultivated trees. The American hazelnuts are of two other species.
2. (Science: zoology) filbert gall, a gall resembling a filbert in form, growing in clusters on grapevines. It is produced by the larva of a gallfly (Cecidomyia).
Origin: Perh. Fr. Fill _ bread, as filling the bread or husk; cf. G. Bartnuss (lit, bread nut) filbert; or perh. Named from a St.Philibert, whose day, Aug. 22, fell in the nutting season.