The Collaborative International Dictionary
Semidome \Sem"i*dome`\, n. (Arch.) A roof or ceiling covering a semicircular room or recess, or one of nearly that shape, as the apse of a church, a niche, or the like. It is approximately the quarter of a hollow sphere.
n. (context architecture English) Half of a dome ("cut" vertically), used to cover a semicircular area.
Usage examples of "semidome".
And from those semidomes, it was impossible not to look farther yet, up and up and up into the great central dome overhead, from which Phos himself surveyed his worshipers.
Columns, walls, arches, ancillary semidomes - all smoothly led the eye up to the great dome, and that was a miracle in itself.