Where does “castoreum” come from?

castoreum (Latin) comes from Latin Castor, from Ancient Greek Κάστωρ, from Doric Greek κάστον.

castoreum (Latin): castoreum, castor sac exudate

Definitions

castoreum traces back through two separate lines of ancestry.

Step	Language	Word	Meaning
1	Latin	Castor	Castor
2	Ancient Greek	Κάστωρ	Castor
3	Doric Greek	κάστον	—

Step	Language	Word	Meaning
1	Ancient Greek	καστόριον	castoreum; beaver; the fur of the beaver
2	Ancient Greek	-ῐον	diminutive suffix; "suffix forming...
3	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems