bulla

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A round seal affixed to a papal bull.
2. n. Pathology A large blister or vesicle.

Century Dictionary and Cyclopedia

1. n. An ornament in the form of capsule or locket, in use among the ancient Romans, who adopted it from the Etruscans. It was worn especially around the neck as an amulet by Roman children, both boys and girls, its protective virtue being supposed to reside either in its precious material or in some substance inclosed within it. It was of gold in the families of the nobly born and the rich, and of commoner material among others. It was laid aside by young men upon attaining maturity, and dedicated to Hercules or to the household lares; by young women it was dedicated to Juno.
2. n. A seal attached to a document. Specifically— A seal used by the emperors of Constantinople, and by the early emperors of the Holy Roman (German) Empire, and by other sovereigns.
3. n. Any ornament of rounded form, especially if suspended, such as those which are attached by small chains to the Hungarian crown.
4. n. In pathology, a bleb or portion of epidermis raised by the extravasation of a transparent watery fluid, as in erysipelas, etc.
5. n. In anatomy, an inflated portion of the bony external meatus of the ear, forming a more or less well-marked prominence on each side at the base of the skull of many animals, usually constituted by a bulbous tympanic bone. Also called bulla ossea. See extract.
6. n. [capitalized] A genus of tectibranchiate (or pleurobranchiate) gastropods, to which very different limits have been assigned. By the old conchologists not only were most of the tectibranchiates included, but also various other gastropods having shells like or supposed to be like them were referred to the genus.

Wiktionary

1. n. medicine A blister, vesicle, or other thin-walled cavity or lesion.
2. n. archaeology A clay envelope or hollow ball, typically with seal impressions or writing on its outside indicating its contents.
3. n. historical In ancient Rome, a kind of amulet or boss.
4. n. Later, handwritten document from the papal chancellery.

GNU Webster's 1913

1. n. (Med.) A bleb; a vesicle, or an elevation of the cuticle, containing a transparent watery fluid.
2. n. (Anat.) The ovoid prominence below the opening of the ear in the skulls of many animals.
3. 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.
4. n. (Zoöl.) A genus of marine shells. See Bubble shell.

WordNet 3.0

1. n. (pathology) an elevation of the skin filled with serous fluid
2. n. the round leaden seal affixed to a papal bull