Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A tough, insoluble protein substance that is the chief structural constituent of hair, nails, horns, and hooves.

from The Century Dictionary.

  • noun Same as ceratin.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Physiol. Chem.) A sulfur-containing fibrous protein constituting the main structural protein of hard epidermal tissues, such as horn, hair, feathers, nails, claws, hoofs, and the like. It is an insoluble substance, and, unlike elastin, is not dissolved even by gastric or pancreatic juice. By decomposition with sulphuric acid it yields leucine and tyrosine plus various other acid-stable amino acids. The amino acid composition varies, but it usually has a high percentage of cystine, which stabilizes and insolubilizes the protein by forming intrachain linkages. A softer form of keratin is present in the epidermis and whalebone. Called also epidermose.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun biochemistry A protein which hair and nails are comprised of.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair, feathers, nails, and hooves

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[Greek keras, kerāt-, horn; see ker- in Indo-European roots + –in.]

Examples

  • There are a number of hair-straightening salon treatments besides Brazilian Blowout on the market, some of which are called "keratin treatments" and "Brazilian treatments."

    Calls for FDA to Regulate Hair Straighteners

  • Hair is made up mostly of a protein called keratin, which is the same material that makes up hooves, claws and fingernails.

    Archive 2006-10-01

  • Hair is made up mostly of a protein called keratin, which is the same material that makes up hooves, claws and fingernails.

    Ancient Egyptian hair dye - technology finally catches up

  • The plate of the nail is composed of a substance called keratin, which is produced by amino acids.

    CreationWiki - Recent changes [en]

  • The plate of the nail is composed of a substance called keratin, which is produced by amino acids.

    CreationWiki - Recent changes [en]

  • The plate of the nail is composed of a substance called keratin, which is produced by amino acids.

    CreationWiki - Recent changes [en]

  • For example, Justin R. Barone, a research scientist at the U.S. Department of Agriculture’s Environmental Quality Laboratory in Beltsville, MD, and colleagues have found that chicken-feather keratin is ideal for strengthening composites.

    Chicken feathers no longer for the birds

  • For example, Justin R. Barone, a research scientist at the U.S. Department of Agriculture’s Environmental Quality Laboratory in Beltsville, MD, and colleagues have found that chicken-feather keratin is ideal for strengthening composites.

    Archive 2006-09-17

  • This is when the buds of the tongue kick into overproduction of a substance called keratin, which causes the buds to grow longer than normal.

    Dr. Harold Katz: Bad Breath and Your Tongue

  • This is when the buds of the tongue kick into overproduction of a substance called keratin, which causes the buds to grow longer than normal.

    Dr. Harold Katz: Bad Breath and Your Tongue

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