The Etymology of Carob
Carob entered English around 1380 from Old French carobe, which traces back through Medieval Latin carrubium to Arabic kharrūbah, the pod of the Mediterranean evergreen tree Ceratonia siliqua. The tree has been cultivated in the eastern Mediterranean for at least four thousand years; its leathery pods contain a sweet pulp and hard, glossy brown seeds. Those seeds carry a curious linguistic legacy: they are remarkably uniform in weight, around 0.2 grams each, and ancient jewellers used them as a counterweight standard for weighing gold and gemstones. The Arabic qīrāṭ for one such seed-weight became Greek keration and eventually English carat — the same word now used for diamond weight and gold purity. So carat the unit and carob the tree are linguistic twins. In the 20th century carob powder gained popularity as a caffeine-free, naturally sweet substitute for cocoa, particularly in health-food contexts. Spanish algarroba and Italian carruba preserve the Arabic original more closely than English does.