Cupola

Webster's Dictionary

(1): (n.) A furnace for melting iron or other metals in large quantity, - used chiefly in foundries and steel works.

(2): (n.) A revolving shot-proof turret for heavy ordnance.

(3): (n.) A roof having a rounded form, hemispherical or nearly so; also, a ceiling having the same form. When on a large scale it is usually called dome.

(4): (n.) The top of the spire of the cochlea of the ear.

(5): (n.) A small structure standing on the top of a dome; a lantern.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature

(Ital.), a concave ceiling, either hemispherical or of any other curve, covering a circular or polygonal area; also a roof, the exterior of which is of either of these forms, more usually called a dome, and in Latin tholus. — Parker, Gloss. of Architect. s.v.