\Cu"po*la\ (k?"p?-l?), n.; pl. {Cupolas} (-l?z). [It.
cupola, LL. cupula, cuppula (cf. L. cupula little tub). fr.
cupa, cuppa, cup; cf. L. cupa tub. So called on account of
its resemblance to a cup turned over. See {Cup}, and cf.
{Cupule}.]
1. (Arch.) 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}.
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 revolving shot-proof turret for heavy ordnance.
5. (Anat.) The top of the spire of the cochlea of the ear.