According to The American Heritage Dictionary of the English Language:
a. A domed roof or ceiling.
b. A small structure surmounting a roof.
The word cupola comes from the Latin meaning "little cupo" or little dome,
and originally referred to the small domes atop cathedrals which allowed
light to enter the sanctuary. But we are more familiar with the wonderful
wooden cupolas on American barns and stables and the elegant cupolas on
most public buildings.