\Bul"la\, n.; pl. {Bull[ae]}. [L. bulla bubble. See {Bull}
an edict.]
1. (Med.) A bleb; a vesicle, or an elevation of the cuticle,
   containing a transparent watery fluid.
2. (Anat.) The ovoid prominence below the opening of the ear
   in the skulls of many animals; as, the tympanic or
   auditory bulla.
3. A leaden seal for a document; esp. the round leaden seal
   attached to the papal bulls, which has on one side a
   representation of St. Peter and St. Paul, and on the other
   the name of the pope who uses it.
4. (Zo["o]l.) A genus of marine shells. See {Bubble shell}.