filbert: [14] Hazelnuts begin to ripen around the end of August, and so in medieval times they were named after Saint Philibert, a 7th-century Frankish abbot whose feast day falls on the 22nd of that month. Thus in Anglo-Norman they were *noix de Philibert or noix de filbert – whence English filbert. [filbert etymology, filbert origin, 英语词源]