cupola

(architecture) A dome-shaped ornamental structure located on top of a larger roof or dome.

(military, railroad) A small turret, usually on a hatch of an armoured fighting vehicle.

(geology) An upward-projecting mass of plutonic rock extending from a larger batholith.

(geometry) 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.

A type of furnace used for smelting.

(anatomy) A small cap over a structure that is shaped like a dome or inverted cup.

(railways, Canada, dated) 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.