Definition of KERATIN (original) (raw)
: 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
Wool fibers are composed of keratin proteins bundled into microfibrils.—A. Goho
compare keratinocyte
Examples of keratin in a Sentence
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Also, consider tacking on other treatments like keratin or other straightening systems to help give the look structure. —Diana Tsui, Footwear News, 3 May 2026 Just like human fingernails and hair, scutes are made of keratin. —Jenny Staletovich, Miami Herald, 2 May 2026 According to Korean hair expert Hyerin Jeon, this shampoo features 10,000 ppm of 10 different proteins, including collagen and keratin, delivering salon-grade conditioning at home. —Iman Balagam, Vogue, 27 Apr. 2026 Membranes tested on human bones cells in laboratory Researchers developed membranes using keratin extracted from wool and chemically treated them to create stable, durable scaffolds. —Prabhat Ranjan Mishra, Interesting Engineering, 27 Apr. 2026 See All Example Sentences for keratin
Word History
Etymology
borrowed from German Keratin, from Greek kerat-, stem of kéras "horn" + German -in -in entry 1 — more at kerato-
Note: The term was introduced by the German physician and chemist Johann Franz Simon (1807-43) in Handbuch der angewandten medizinischen Chemie, 1. Theil, Medizinisch-analytische Chemie (Berlin, 1840), p. 49.
First Known Use
circa 1849, in the meaning defined above
Time Traveler
The first known use of keratin was circa 1849
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Cite this Entry
“Keratin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/keratin. Accessed 13 May. 2026.
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