1. A tree of several species, constituting the genus Betula; as, the white or common birch (B. Alba) (also called silver birch and lady birch); the dwarf birch (B. Glandulosa); the paper or canoe birch (B. Papyracea); the yellow birch (B. Lutea); the black or cherry birch (B. Lenta).
(Science: zoology) see ruffed grouse. Birch wine, wine made of the spring sap of the birch. Oil of birch. An oil obtained from the bark of the common European birch (betula alba), and used in the preparation of genuine (and sometimes of the imitation) Russia leather, to which it gives its peculiar odour. An oil prepared from the black birch (B. Lenta), said to be identical with the oil of wintergreen, for which it is largely sold.