A whirring sound, such as a telephone ringing tone or the sound of cogs turning. (Oxford Dictionaries)
If someone has a burr, they speak English with a regional accent in which ‘r’ sounds are pronounced more strongly than in the standard British way of speaking. (Collins Dictionary)
A burr is the part of some plants which contains seeds and which has little hooks on the outside so that it sticks to clothes or fur. (Collins Dictionary)
A rough or prickly envelope of a fruit. (Merriam – Webster)
A plant that bears burs. (Merriam – Webster)
Noogoora burr control.
The difference between burr and blade coffee grinders.