noun.
A tough, insoluble protein substance that is the chief structural constituent of hair, nails, horns, and hooves.
The Century Dictionary and Cyclopedia
noun.
Same as ceratin.
the GNU version of the Collaborative International Dictionary of English
noun.
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.
noun.
A protein which hair and nails are comprised of.
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
Word Usage
"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.""