Wood of deciduous forest trees of the genus Quercus (family Fagaceae), especially Quercus robur (also called common oak, English oak, or pedunculate oak) and Quercus petraea (also called durmast oak or sessile oak). Oak was the favoured wood of North European furniture-makers throughout the Middle Ages, and although it was displaced by walnut in the 17th century for high status furniture, it continued to be used in Northern Europe and America for vernacular furniture.