barbule
/ˈbɑrbjul/
noun
- A small, hairlike projection on a feather barb that helps lock the feather together.
- When a bird preens, it realigns the barbules to keep its feathers smooth and waterproof.
- Each barb on a feather is covered with tiny barbules that hook together like Velcro.
- Under a microscope, you can see the barbules branching off the main shaft of the feather.