burr

burr /ˈbɚ/ noun
plural burrs
burr
/ˈbɚ/
noun
plural burrs
Britannica Dictionary definition of BURR
[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
3 
: a strong way of pronouncing r that is used by some speakers of English especially in northern England and in Scotland — usually singular

a burr in/under the saddle

US, informal
: someone or something that is a constant cause of trouble or annoyance