-verb (used without object)
1. to take its origin or rise; begin; start; arise: The practice originated during the Middle Ages. 2. (of a train, bus, or other public conveyance) to begin a scheduled...
Chitin is a nitrogen-containing polysaccharide that forms a semitransparent horny substance and is a principal constituent of the exoskeleton, or outer covering, of insects, crustaceans, and...