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}]
     v : remove the burls from cloth
Source: WordNet® 2.0