Chitin

Part of speech: noun

Pronunciation: /ˈkaɪtɪn/

Definitions

1. A tough, fibrous substance present in the exoskeletons of arthropods, the protective coverings of some mollusks, and the structural components of fungal cell walls
2. This biomolecule is a key structural element in the shells of crustaceans, the cuticles of various insects, and the cell walls of specific fungi
3. A resilient and complex carbohydrate found in the exoskeletons of insects and crustaceans, as well as in the walls of certain fungi and the coverings of some mollusks

Etymology: Chitin is one of the few common biological materials named after a garment. In ancient Greek, "khitṓn" meant a tunic worn next to the skin, and it was later applied to the shell of a mollusk, which the Latin "chitōn" carried over into zoological use. The French chemist and naturalist who introduced "chitine" took the name from that Latin term, reasoning that the hard covering of insects and crustaceans resembled the armour of a chiton. English borrowed the word from French in the nineteenth century, and it now names the tough polysaccharide that forms the exoskeletons of insects, spiders and crabs. The link to the garment survives only in the word's history, since the substance itself has nothing to do with cloth.