Bual (or Boal) is a variety of grape used in the production of medium-rich fortified wines from Madeira Island. According to the Geisenheim DNA Database, the name is a synonym for each of at least four white wine-producing varieties. The name can be applied to any one of several varieties including Codega , Dõna Branco , Rabigato , or Semillon. The vines are also common in Portugal and Spain, where the fruit is used in the same way for fortified wines.
It gives its name to one of the types of Madeira wine.
