Bulla

Lat. [Gr. boubalos, boulla.] A seal used by the Roman emperors, during the lower empire; and which was of four kinds, gold, silver, wax and lead. These are described by Spelman in detail. A letter, brief or charter sealed with such a seal, (literae bullatae.) Spelman. A brief, mandate or bull of the pope, having usually a leaden, but sometimes a golden seal. Id. Blount.

Cowell.