Oak

(ok) [AS., ac, oak]. A genus of trees, Quercus, of the order Cupuliferse. The bark of Quercus alba (U. S. P., Quercus cortex and of Quercus robur, B. P.) and other species, contains a peculiar tannic acid known as quercitannic acid, and a bitter principle, quercin, and is used as an astringent tonic, especially in the form of the oak-bath. It has also been employed in leukorrhea, hemorrhoids, and prolapse of the rectum. O.-bark (Quercus alba, U. S. P.; Quercus cortex, B. P.) is an astringent tonic containing tannic acid, and is mostly employed in washes and decoctions for external use. 453