| Noun | 1. | ceratin - a fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair, feathers, nails, and hooves feather, plumage, plume - the light horny waterproof structure forming the external covering of birds hair - a covering for the body (or parts of it) consisting of a dense growth of threadlike structures (as on the human head); helps to prevent heat loss; "he combed his hair"; "each hair consists of layers of dead keratinized cells" horn - the material (mostly keratin) that covers the horns of ungulates and forms hooves and claws and nails albuminoid, scleroprotein - a simple protein found in horny and cartilaginous tissues and in the lens of the eye |