carbuncle

noun

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