Definition of burr noun from the Oxford Advanced Learner's Dictionary

burr

noun

bɜː(r)

bɜːr

1 [usually singular] a strong pronunciation of the ‘r’ sound, typical of some accents in English; an accent with this type of pronunciationShe speaks with a soft West Country burr.2 [usually singular] the soft regular noise made by parts of a machine moving quickly

Synonym

whirr3 (also bur) [countable] the seed container of some plants which is covered in very small hooks that stick to clothes or fur