A peculiar bitter orange-brown substance, with strong, penetrating odor, found in two sacs between the anus and external genitals of the beaver; castor; -- used in medicine as an antispasmodic, and by perfumers.
Castoreum is the glandular secretion of the beaver. Today, it is used in trapping, some perfumes, and as a flavoring in chewing gum. Although modern medical use of castoreum is rare, it was a commonplace 'cure' in archaic times.