noun
- a tough, fibrous protein that forms the main structural component of hair, nails, horns, hooves, and the outer layer of skin
Usage: biology
Examples
- Keratin makes hair strong and flexible.
- The outer layer of skin contains keratin to protect the body.
- Animal horns and hooves are made primarily of keratin.
- Hair treatments often claim to restore keratin to damaged strands.
- Keratin is what gives fingernails their hardness.
- Birds’ feathers and beaks contain keratin as their main protein.