castoreum
From LSJ
castŏrĕum: ei, n. 1. castor,
I castor or castoreum, a secretion of the beaver having a strong odor, Plin. 8, 30, 47, § 109; Lucr. 6, 794; Cels. 6, 7, 8; Scrib. 3.—In <number opt="n">plur.</number>, Verg. G. 1, 59; Plin. 32, 9, 31, § 101; Nemes. C. 224.