Definition of keratin in English:



  • A fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc.

    • ‘Their skin is covered with non-overlapping scales composed of the protein keratin and often studded with bony plates called scutes.’
    • ‘The structures had probably been covered with keratin, the same protein found in fingernails, horns, and claws.’
    • ‘Mammalian hair, made of a protein called keratin, serves at least four functions.’
    • ‘The slightly flattened spikes were covered with keratin, the same protein found in horns, fingernails, and claws.’
    • ‘The mature nail is a plate of the protein keratin which is also present in hair and skin.’
    • ‘Chemical constituents include keratin and eukeratin as well as other proteins, peptides and free amino acids.’
    • ‘Gecko spatulae are made of keratin, the protein in human hair.’
    • ‘Baleen is made of keratin, the same protein that makes up hair and fingernails, and is strong, yet elastic.’
    • ‘Amino acids are absorbed by the body to help build keratin, the main protein in hair.’
    • ‘Each hair is made of tough and stretchable protein called keratin, manufactured by the hair follicle.’
    • ‘Hair is composed of non-living tissue, mostly of a fibrous protein known as keratin and is devoid of nerves.’
    • ‘Cells are laced with a network of fibres more rigid than the rope-like structural proteins collagen and keratin.’
    • ‘Animal hair fibers consist of a protein known as keratin.’
    • ‘Your fingernails are composed of layers of keratin, a protein also found in hair and skin.’
    • ‘Androgens are also responsible for the increased growth in body hair and an increased shedding of keratin, a protein that can block pores and the flow of sebum.’
    • ‘Cat claws are made of keratin, a protein also found in human nails.’
    • ‘Actin and keratin both share with byssal threads a tendency to recover initial modulus and stress upon relaxation.’
    • ‘Fungal infections usually affect the skin because they live off keratin, a protein that makes up skin, hair and nails.’
    • ‘Dermatophytes are fungi that can cause infections of the skin, hair and nails because of their ability to feed on keratin.’
    • ‘They are unable to grow in living tissues but instead can multiply in structures containing keratin.’


Mid 19th century: from Greek keras, kerat- horn + -in.