Cupola

Part of speech: noun (n.)

1. A roof having a rounded form, hemispherical or nearly so; also, a celing having the same form. When on a large scale it is usually called dome.

2. A small structure standing on the top of a dome; a lantern.

3. A furnace for melting iron or other metals in large quantity, -- used chiefly in foundries and steel works.

4. A revoling shot-proof turret for heavy ordnance.

5. The top of the spire of the cochlea of the ear.