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).
- Any of various deciduous trees or shrubs of the genus Betula, native to the Northern Hemisphere and having unisexual flowers in catkins, alternate, simple, toothed leaves, and bark that often peels in thin papery layers.
- The hard, close-grained wood of any of these trees, used especially in furniture, interior finishes, and plywood.
- A rod from a birch, used to administer a whipping.
- To whip with or as if with a birch.