Bur \Bur\, Burr \Burr\ (b[^u]r), n. [OE. burre burdock; cf.
         Dan.
   borre, OSw. borra, burdock, thistle; perh. akin to
         E. bristle
   (burr- for burz-), or perh. to F. bourre
         hair, wool, stuff;
   also, according to Cotgrave, "the
         downe, or hairie coat,
   wherewith divers herbes, fruits,
         and flowers, are covered,"
   fr. L. burrae trifles, LL.
         reburrus rough.]
   1. (Bot.) Any rough or prickly envelope
         of the seeds of
      plants, whether a pericarp, a
         persistent calyx, or an
      involucre, as of the chestnut
         and burdock; a seed vessel
      having hooks or prickles.
         Also, any weed which bears burs.
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            Amongst rude burs and thistles.       --Milton.
     
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            Bur and brake and brier.              --Tennyson.
     
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   2. The thin ridge left by a tool in
         cutting or shaping metal.
      See Burr, n., 2.
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         Webster]

   3. A ring of iron on a lance or spear. See Burr, n., 4.
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         Webster]

   4. The lobe of the ear. See Burr, n., 5.
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         Webster]

   5. The sweetbread.
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          6. A clinker; a partially vitrified brick.
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         Webster]

   7. (Mech.)
      (a) A small circular saw.

              (b) A triangular chisel.
      (c) A drill with a
         serrated head larger than the shank; --
          especially a small drill bit used by dentists.
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   8. [Cf. Gael. borr, borra, a knob,
         bunch.] (Zool.) The round
      knob of an antler next to a
         deer's head. [Commonly written
      burr.]
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         Webster]

   Bur oak
         (Bot.), a useful and ornamental
         species of oak
      (Quercus macrocarpa) with ovoid
         acorns inclosed in deep
      cups imbricated with pointed
         scales. It grows in the
      Middle and Western United
         States, and its wood is tough,
      close-grained, and
         durable.

   Bur reed
         (Bot.), a plant of the genus
         Sparganium, having
 
             long ribbonlike leaves.
     
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