What does keratin mean?
Keratin is a strong, fibrous protein that gives hair, nails, and the outer surface of the skin their structure and resilience. It also occurs in the hooves, horns, claws, and feathers of many animals. In scientific contexts, keratin usually refers to this biological material, including the different keratins found in various tissues. In hair-care and beauty marketing, the word can mean treatments or products that use keratin or keratin-derived ingredients to make hair appear smoother and stronger. The word is especially useful because it connects familiar features such as fingernails and animal hooves to a broader principle of biology: specialized surface tissues are often strengthened by the same recurring structural proteins.
nounA tough, fibrous structural protein that forms the main component of hair, nails, hair, and the outer layer of skin, and also occurs in hooves, horns, and feathers. In materials and beauty contexts, the term may refer to products or treatments made from keratin-rich sources.
- The fibrous structural protein that is a principal component of hair, nails, the outer layer of skin, and related structures.
- A tough, keratin-rich material or substance, especially when used in hair-care or cosmetic products.
- Any of various related proteins classified by their structure and occurrence in biological tissues.
"The winter cold left her hair brittle by reducing the moisture that helps maintain its natural keratin structure."
"The animal's hooves are made largely of keratin, the same type of protein found in human fingernails."
"The salon advertised a keratin treatment intended to smooth the client's hair."
Usually uncountable in general and biological usage; the plural is chiefly used in technical contexts to refer to distinct keratin proteins or types.
"Researchers classified the keratins found in the hair and skin of different mammalian species."
Keratin is the protein that turns scales into armor: it helps build the resilient surfaces of hair, nails, horns, hooves, and feathers.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does keratin come from?
The word keratin comes from Greek keras, meaning “horn,” through forms associated with keratinos, meaning “horny” or “horn-like.” English borrowed the term in the 19th century for a substance associated with horns and related structures. The Greek root also appears in technical words such as keratoderma and keratoplasty, as well as in ceramic, which ultimately derives from a Greek word for clay or horn-like material.
Related word forms
How keratin is actually used
In biology and medicine, the term is usually a mass noun: researchers discuss keratin in hair, skin, or nails, while the plural keratins is used in more specialized or taxonomic contexts. In consumer contexts, it often refers to keratin-derived treatments and cosmetic products, and such uses are sometimes associated with marketing language.