Corylus maxima

filbert 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.] 1. (Bot.) The fruit of the {Corylus Avellana} or {Corylus maxima}, also called the hazel; the hazelnut. It is an oval nut, containing a kernel that has a mild, farinaceous, oily taste, agreeable to the palate. [1913 Webster]

Note: In England filberts are usually large hazelnuts, especially the nuts from selected and cultivated trees. The American hazelnuts are of two other species, {Corylus Americana} and {Corylus cornuta}, and are also sometimes called filberts. [1913 Webster +PJC]

2. (Bot.) The tree bearing the filbert; the hazelnut tree. [PJC]

{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}). [1913 Webster]