"rough sound of the letter -r-" (especially that common in Northumberland), 1760, later extended to "northern accented speech" in general. Possibly the sound of the word is imitative of the speech peculiarity itself, or it was adapted from one of the senses of bur (q.v.), perhaps from the phrase to have a bur in (one's) throat (late 14c.), which was a figure of speech for "feel a choking sensation, huskiness." OED says the Scottish -r- is a lingual trill, not a true burr.
实用例句
1. I take it you're a friend of the Kellings, Mr Burr.
伯尔先生，想必您是凯林家的朋友吧？
来自柯林斯例句
2. She speaks with a soft West Country burr.
她说话带有一种西部地区浓重r音的口音。
来自《权威词典》
3. She speaks with a Scottish burr.
她讲话时带苏格兰人的颤音r音.
来自《简明英汉词典》
4. The last part introduces the burr _ distribution with three parameters.