Castoreum is an odorous secretion obtained from certain glands of the beaver.The word beaver is derived from the Sanskrit word babhru, bebras in Lithuanian (an old Indo-European language), biber in German, bever in Middle English and fiber in Latin.
The word castoreum is derived from the Greek word kastor (kastorion), castor in French.
Although the term castor is used interchangeably with castoreum in dictionaries, castoreum is the preferred term in perfumery to denote the perfume material obtained from the beaver.
There are two species of beavers (belonging to the family Castoridae) of importance in perfumey. The first is Castor fiber L, (Siberian beaver), found in Russia and in many parts of Europe, and the second is Castor canadensis (Canadian beaver), found in Canada and the northern United States.