\Fil"bert\, n. [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.] (Bot.)
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.

Note: In England filberts are usually large hazelnuts,
      especially the nuts from selected and cultivated trees.
      The American hazelnuts are of two other species.

{Filbert gall} (Zo["o]l.), a gall resembling a filbert in
   form, growing in clusters on grapevines. It is produced by
   the larva of a gallfly ({Cecidomyia}).