Keratins

Part of speech: noun

Definitions

1. A category of fibrous proteins prominent in skin, hair, and nails that provide structural integrity and protection
2. Types of proteins found in various parts of the body, revered for their role in forming tough protective barriers
3. Structural proteins that compose the outer layer of skin, hair, and nails, crucial for maintaining biological resilience and durability

Etymology: Keratin is one of the few common biological terms whose name is built from a single Greek word for a familiar object: "kéras", meaning "horn". The chemist who coined it in German, "Keratin", was naming the substance after the material that makes up horn, hooves, and the like, and the English term was borrowed from that German coinage. The suffix "-in" is the standard chemical ending used for proteins and other organic substances, so the word simply means "the horny stuff." The word is also a doublet of "carat", a surprising relative. Both descend from the same Greek "kéras" (horn), and the carat name came from the seed of the carob tree, which was used as a small unit of weight. Two very different words, one from horn and one from a bean, are cousins through the same ancient root. Because "keratins" is simply the plural of "keratin", it refers to the several distinct proteins chemists have identified in this family, rather than to a single compound.