cupola

noun8

1. •
   A dome-shaped ornamental structure located on top of a larger roof or dome.

   • the light falling dimly through the foggy cupola. — 1886
2. •
   A small cap over a structure that is shaped like a dome or inverted cup.

   • From each anterior cupola there projects forwards the processus prenasalis lateralis inferior. — 1937
3. •
   A small turret, usually on a hatch of an armoured fighting vehicle.
4. •
   (old-fashioned) a small viewing window in the top of the caboose for looking over the train, or the part of the caboose where one looks through this window.
5. •
   A type of furnace used for smelting.

   • The cupola has a small cylindrical chimney-like bore that is lined with a refractory material. — 2008
6. •
   A body of members of the Sicilian Mafia who make decisions and settle disputes.
7. •
   A solid formed by joining two polygons, one (the base) with twice as many edges as the other, by an alternating band of isosceles triangles and rectangles.
8. •
   An upward-projecting mass of plutonic rock extending from a larger batholith.