hemicyclium
[ hem-i-sik-lee-uh m ]
/ ˌhɛm ɪˈsɪk li əm /
noun
a sundial in the form of a concave quarter sphere having a rodlike gnomon lying within one radius and marked on its surface with arcs that lie in the same plane as the gnomon.
Also
hemicycle.
Origin of hemicyclium
From Latin; see origin at
hemicycle