The Collaborative International Dictionary of English v.0.48:

Cupola \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.
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   2. A small structure standing on the top of a dome; a
      lantern.
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   3. A furnace for melting iron or other metals in large
      quantity, -- used chiefly in foundries and steel works.
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   4. A revolving shot-proof turret for heavy ordnance.
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   5. (Anat.) The top of the spire of the cochlea of the ear.
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