burr 
/ˈbɚ/ noun
plural burrs /ˈbɚ/ noun [count] 1 also bur : a rough covering of a nut or seed ◊Burrs often have small hooks that stick to clothing and fur. 2 : a rough area on a piece of metal that is left after the metal is cut
▪ a tool that can cut through steel leaving a smooth edge and no burrs 3 : a strong way of pronouncing r that is used by some speakers of English especially in northern England and in Scotland — usually singular ▪ He speaks with a Scottish burr.
▪ a tool that can cut through steel leaving a smooth edge and no burrs
a burr in/under the saddle
US, informal : someone or something that is a constant cause of trouble or annoyance
▪ He was a burr in the saddle of the competition. ▪ She's been a burr under their saddle for many years.
▪ He was a burr in the saddle of the competition. ▪ She's been a burr under their saddle for many years.
