The sources differ as to the origin of the surname; it could be a phytonymic surname, possibly derived from the term cassus, meaning "oak", with presence in the plain of Lombardy.

E. Rossoni, on the other hand, considers that it derives from a nickname of uncertain origin, and rules out as unlikely both the connection with the locality of Cassis in the south of France and the link with the term cassis, referring to the aroma of blackcurrant. Rossoni also notes that in the 18th century the Counts Cassis Faraone are already documented in the Udine area, which places the surname in the northeast of Italy in an early period. The presence of the surname is also recorded in the Bergamo area, specifically in the localities of Calcinate and Cavernago.