Source : Webster's Revised Unabridged Dictionary (1913)

Betulin \Bet"u*lin\, n. [L. betula birch tree.] (Chem.)
   A substance of a resinous nature, obtained from the outer
   bark of the common European birch ({Betula alba}), or from
   the tar prepared therefrom; -- called also {birch camphor}.
   --Watts.

Birch \Birch\ (b[~e]rch), n.; pl. {Birches} (-[e^]z). [OE.
   birche, birk, AS. birce, beorc; akin to Icel. bj["o]rk, Sw.
   bj["o]rk, Dan. birk, D. berk, OHG. piricha, MHG. birche,
   birke, G. birke, Russ. bereza, Pol. brzoza, Serv. breza, Skr.
   bh[=u]rja. [root]254. Cf. 1st {Birk}.]
   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}).

   2. The wood or timber of the birch.

   3. A birch twig or birch twigs, used for flogging.

   Note: The twigs of the common European birch (B. alba), being
         tough and slender, were formerly much used for rods in
         schools. They were also made into brooms.

               The threatening twigs of birch.    --Shak.

   4. A birch-bark canoe.

   {Birch of Jamaica}, a species ({Bursera gummifera}) of
      turpentine tree.

   {Birch partridge}. (Zo["o]l.) See {Ruffed grouse}.

   {Birch wine}, wine made of the spring sap of the birch.

   {Oil of birch}.
      (a) 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 odor.
      (b) An oil prepared from the black birch ({B. lenta}),
          said to be identical with the oil of wintergreen, for
          which it is largely sold.