ker·​a·​tin | \ ˈker-ə-tən How to pronounce keratin (audio) \

Definition of keratin

: 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

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Other Words from keratin

keratinous \ kə-​ˈra-​tə-​nəs How to pronounce keratinous (audio) \ adjective

Examples of keratin in a Sentence

Recent Examples on the Web Six of the seven species have hard shells fused to their ribs and overlaid with keratin scutes. National Geographic, "Sea survivors," 10 Oct. 2019 With a keratin lash lift, more protein is added back into the lash, Imani says. Sara Spruch-feiner, Town & Country, "What Is a Lash Lift and Tint?," 7 Mar. 2020 Pangolins are insect-eating mammals that are covered in protective keratin scales. Mark Olalde, USA TODAY, "Climate Point: Nepal is melting, and Trump wants to mine the moon," 10 Apr. 2020 Pangolins are mostly covered in thick scales of keratin—the substance human fingernails are made of—that protect their bodies from predators like leopards. National Geographic, "Sunda pangolin," 19 Mar. 2020 The horns are made of sheaths of keratin, like true horns, but shed every year like a true antler. Matt Wyatt,, "Airlifts have Texas pronghorn on the rise," 13 Feb. 2020 Much of its strength comes from a material called keratin. Svenja Lohner, Scientific American, "Test the Strength of Hair," 28 Nov. 2019 In birds, melanosomes, which are little packets of melanin pigment surrounded by keratin protein create this iridescence effect. Kate Baggaley, Popular Science, "Hummingbirds get their wild coloring from ‘air-filled pancakes’ in their feathers," 10 Jan. 2020 Rhinos are killed for their horns, which consist of keratin similar to human hair and nails and are used in traditional medicines in parts of Asia. USA TODAY, "The Sumatran rhino is now extinct in Malaysia after lone survivor succumbs to cancer," 25 Nov. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'keratin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of keratin

circa 1849, in the meaning defined above

History and Etymology for keratin

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.

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Time Traveler for keratin

Time Traveler

The first known use of keratin was circa 1849

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Cite this Entry

“Keratin.” Dictionary, Merriam-Webster, Accessed 23 Oct. 2020.

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More Definitions for keratin


ker·​a·​tin | \ ˈker-ət-ən How to pronounce keratin (audio) \

Medical Definition of keratin

: 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

More from Merriam-Webster on keratin

Britannica English: Translation of keratin for Arabic Speakers Encyclopedia article about keratin

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