keratin
noun
ker·a·tin
ˈker-ə-tən 
: any of various sulfur-containing, fibrous, acidic or basic proteins chiefly of epithelial cells and tissues that are relatively insoluble and resistant to degradation, form filaments which assemble into bundles to provide structural support, and are the primary component of hair, nails, horns, claws, hooves, quills, scales, feathers and the epidermal layer of skin
Note: In addition to its structural properties, keratin also plays a role in cell growth and proliferation, cellular transport of substances, and intercellular communication.
Rhino horn is not actually horn but densely compacted fibers of keratin, a protein found in hair and fingernails.—
Maryanne Vollers
Maryanne VollersWool fibers are composed of keratin proteins bundled into microfibrils.—A. Goho
compare keratinocyte
A. GohoExamples of keratin in a Sentence
Recent Examples on the Web
Glycine, a key amino acid, helps relink keratin chains to reduce breakage and seal split ends.
—Deanna Pai, Vogue, 14 July 2024
Key Ingredients: Biotin, keratin, chia seed oil Sulfate-Free: Yes
Size: 10 fl. oz.
—Emily Orofino, Vogue, 2 Oct. 2024
Now, about that ashwagandha: Though the ingredient is thought to help stimulate keratin production and is commonly used in hair potions promising thicker, stronger, healthier hair, Nutrafol’s version of the adaptogen is a bit different.
—Jenny Berg, Allure, 23 Oct. 2024
This innovative product is like a bond builder for your nails, and is formulated with a patented Ulti-Plex Technology that helps repair and build keratin bonds for stronger, healthier nails.
—Karina Hoshikawa, refinery29.com, 17 Sep. 2024
See all Example Sentences for keratin 
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Deanna Pai, Vogue, 14 July 2024
Key Ingredients: Biotin, keratin, chia seed oil Sulfate-Free: Yes
Size: 10 fl. oz.
—Emily Orofino, Vogue, 2 Oct. 2024
Now, about that ashwagandha: Though the ingredient is thought to help stimulate keratin production and is commonly used in hair potions promising thicker, stronger, healthier hair, Nutrafol’s version of the adaptogen is a bit different.
—Jenny Berg, Allure, 23 Oct. 2024
This innovative product is like a bond builder for your nails, and is formulated with a patented Ulti-Plex Technology that helps repair and build keratin bonds for stronger, healthier nails.
—Karina Hoshikawa, refinery29.com, 17 Sep. 2024
See all Example Sentences for keratin
Dictionary Entries Near keratin
Cite this Entry
“Keratin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/keratin. Accessed 1 Dec. 2024.
Copy CitationKids Definition
keratin
noun
ker·a·tin
ˈker-ət-ᵊn
: a sulfur-containing protein that makes up hair and horny tissues (as nails)
Medical Definition
keratin
noun
ker·a·tin
ˈker-ət-ən
: any of various sulfur-containing fibrous proteins that form the chemical basis of horny epidermal tissues (as hair and nails) and are typically not digested by enzymes of the gastrointestinal tract see pseudokeratin
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