In architecture, tambour has three meanings.

In classical architecture, a tambour(Frenchfor'drum') is the inverted bell of the Corinthian capital, around which acanthus leaves are carved for decoration.

Corinthian columns from the Pantheon, Rome, c. 114-124 AD

The term also applies to the circular or polygonal wall of a structure that supports a dome, cupola, or lantern, whether on the ground or raised aloft on pendentives; in this sense, it is also called a tholobate.

Dome upon tholobate of the Pennsylvania State Capitol, Harrisburg

Finally, tambour can refer to the cylindrical stone blocks, or drums, that make up a column built in several courses.

Columns of the Parliament House in Helsinki, Finland

Notes