<p><strong>Noun</strong></p><ul><li>any tree or shrub belonging to the genus Quercus, of the beech family, bearing the acorn as fruit.</li><li>the hard, durable wood of an oak tree, used in making furniture and in construction.</li><li>Archaic: the leaves of an oak tree, especially as worn in a chaplet.</li></ul><p><strong>Adjective</strong></p><ul><li>pertaining to or made of oak: an antique oak desk; heavy oak doors with double locks.</li></ul>