dome

DOME, n. [Gr., a house, a plain roof. L.]

1. A building; a house; a fabric; used in poetry.

2. A cathedral.

3. In architecture, a spherical roof, raised over the middle of a building; a cupola.

4. In chemistry, the upper part of a furnace, resembling a hollow hemisphere or small dome. This form serves to reflect or reverberate a part of the flame; hence these furnaces are called reverberating furnaces.