Noun

1. A deep-red or fiery colored garnet or other dark red precious stone, especially when cut cabochon.
   • 1602. Hamlet by William Shakespeare, act 2 scene 2 line 401:

     With eyes like carbuncles, the hellish Pyrrhus...

   • 1611. Old Testament, King James Version, Isaiah 54:12:

     And I will make thy windows of agates, and thy gates of carbuncles, and all thy borders of pleasant stones.

2. An abscess larger than a boil, usually with one or more openings draining pus onto the skin. It is usually caused by bacterial infection.