pepperbox

Short definition from Wiktionary

Noun

1. 1
   A pepper shaker.
2. 2
   A repeating firearm with three or more barrels grouped around a central axis.
3. 3
   A buttress at one side of the court in the game of fives.
4. 4
   A tower capped by a cupola, looking similar to a giant pepper shaker.
5. 5
   Any of the buildings of the Royal Academy and National Gallery in Trafalgar Square, London, having cupolas on the roof.