Cassius \Cas"sius\, n. [From the name of the discoverer, A. Cassius, a German physician of the 17th centry.]

A brownish purple pigment, obtained by the action of some compounds of tin upon certain salts of gold. It is used in painting and staining porcelain and glass to give a beautiful purple color. Commonly called Purple of Cassius.

Source: Webster's Revised Unabridged Dictionary (1913)