n. - A bleb; a vesicle, or an elevation of the cuticle, containing a transparent watery fluid.
n. - The ovoid prominence below the opening of the ear in the skulls of many animals; as, the tympanic or auditory bulla.
n. - 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.
n. - A genus of marine shells. See Bubble shell.