The Collaborative International Dictionary of English v.0.48:

Burl \Burl\, n.
   1. A knot or lump in thread or cloth.
      [1913 Webster]

   2. An overgrown knot, or an excrescence, on a tree; also,
      veneer made from such excrescences.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Burl \Burl\ (b[^u]rl), v. t. [imp. & p. p. Burled (b[^u]rld);
   p. pr. & vb. n. Burling.] [OE. burle stuffing, or a knot in
   cloth; cf. F. bourlet, bourrelet, OF. bourel, a wreath or a
   roll of cloth, linen, or leather, stuffed with flocks, etc.,
   dim. of bourre. [root]92. See Bur.]
   To dress or finish up (cloth); to pick knots, burs, loose
   threads, etc., from, as in finishing cloth.
   [1913 Webster]

   Burling iron, a peculiar kind of nippers or tweezers used
      in burling woolen cloth.
      [1913 Webster]

WordNet (r) 3.0 (2006):

burl
    n 1: the wood cut from a tree burl or outgrowth; often used
         decoratively in veneer
    2: a large rounded outgrowth on the trunk or branch of a tree
    3: soft lump or unevenness in a yarn; either an imperfection or
       created by design [syn: slub, knot, burl]
    v 1: remove the burls from cloth

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "burl":
   bilge, blain, bleb, blister, blob, boss, bow, bubble, bulb, bulge,
   bulla, bump, bunch, button, cahot, chine, clump, condyle, convex,
   dowel, ear, flange, flap, gall, gnarl, handle, hill, hump, hunch,
   jog, joggle, knob, knot, knur, knurl, lip, loop, lump, mole,
   mountain, nevus, nub, nubbin, nubble, papilloma, peg, rib, ridge,
   ring, shoulder, spine, stud, style, tab, tubercle, tubercule,
   verruca, vesicle, wale, wart, welt