castoreum

"beaver," 1398, from O.Fr. castor, from L. castor "beaver," from Gk. Kastor "he who excels," one of the divine twins (with Pollux), worshipped by women in ancient Greece as a healer and preserver from disease. His name was given to secretions of the animal, used medicinally in ancient times. Through this association his name replaced the native L. word for "beaver," which was fiber. Modern castor oil is first recorded 1746; it is made from seeds of the plant Ricinus communis but supposedly possesses qualities (and taste) similar to those of beaver juice, and thus so named.