burl (n.)youdaoicibaDictYouDict[burl 词源字典]
"small knot in wool or cloth," mid-15c., from Old French bourle "tuft of wool," which perhaps is related to the root of bur, or from Vulgar Latin *burrula "small flock of wool," from Late Latin burra "wool."[burl etymology, burl origin, 英语词源]