carbuncle

noun

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