carbuncle

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A painful localized bacterial infection of the skin and subcutaneous tissue that usually has several openings through which pus is discharged.
2. n. A deep-red garnet, unfaceted and convex.
3. n. Obsolete A red precious stone.

Century Dictionary and Cyclopedia

1. n. A beautiful gem of a deep-red color, inclining to scarlet, found chiefly in the East Indies. When held up to the sun it loses its deep tinge, and becomes of the color of a burning coal. It was formerly believed to be capable of shining in darkness. The carbuncle of the ancients in believed to have been a garnet, some varieties of which still go by that name, though the name included also the ruby and the spinel.
2. n. In pathology, a circumscribed inflammation of the subcutaneous connective tissue, resulting in suppuration and sloughing, and having a tendency to extend itself, undermining the skin. It is somewhat similar to a boil, but more serious in its effects.
3. n. In her.: A charge or bearing generally consisting of 8 radiating staffs or scepters, 4 of which are vertical and horizontal and 4 diagonal or saltierwise, and supposed to represent the precious stone carbuncle. Also called escarbuncle.
4. n. The tincture red, when describing a nobleman's escutcheon according to the system of blazoning by precious stones. See blazon, n., 2.
5. n. A whelk or “toddy-blossom” on a drunkard's face.

Wiktionary

1. n. archaic A deep-red or fiery colored garnet or other dark red precious stone, especially when cut cabochon.
2. n. An abscess larger than a boil, usually with one or more openings draining pus onto the skin. It is usually caused by bacterial infection.
3. n. heraldry A charge or bearing supposed to represent the precious stone, with eight sceptres or staves radiating from a common centre; an escarbuncle.

GNU Webster's 1913

1. n. (Min.) A beautiful gem of a deep red color (with a mixture of scarlet) called by the Greeks anthrax; found in the East Indies. When held up to the sun, it loses its deep tinge, and becomes of the color of burning coal. The name belongs for the most part to ruby sapphire, though it has been also given to red spinel and garnet.
2. n. (Med.) A very painful acute local inflammation of the subcutaneous tissue, esp. of the trunk or back of the neck, characterized by brawny hardness of the affected parts, sloughing of the skin and deeper tissues, and marked constitutional depression. It differs from a boil in size, tendency to spread, and the absence of a central core, and is frequently fatal. It is also called anthrax.
3. n. (Her.) A charge or bearing supposed to represent the precious stone. It has eight scepters or staves radiating from a common center. Called also escarbuncle.

WordNet 3.0

1. n. deep-red cabochon garnet cut without facets
2. n. an infection larger than a boil and with several openings for discharge of pus