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Keratin

/ˈkɛrətɪn/noun

The tough fibrous protein that builds hair, nails, horn, hoof and the outer skin.

The Greek roots

κέρας
kéras
horn

Literally: horn-substance

Follow a root:κέρας5 words

The story of the word

Named in the 1840s from the Greek for horn, because horn is very nearly pure keratin, as are claw, feather, hoof and fingernail. The same κέρας is inside rhinoceros, nose-horn, and triceratops. It also gives carat: κεράτιον, a little horn, was the carob seed jewellers used as a counterweight, and the word reached English through Arabic.

How it travelled
Ancient Greek → scientific coinage → English
First recorded
1840s

Same family

rhinoceroskeratitiscarattriceratops

In a sentence

Hair is dead keratin, which is why cutting it does not hurt.

Built on the same root

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