Of or pertaining to, or having the form of, a spheroid.In crystallography, globose; bounded by several convex faces.In entomology, round and prominent, appearing like a ball or sphere partly buried in the surface: as, spheroidal eyes: spheroidal eoxæ.In petrography, noting the cracking or parting of rocks upon shrinking, commonly from cooling, whereby they break into spheroidal masses. It is the same phenomenon as perlitic cracking in volcanic glasses. The term is sometimes used as a synonym of orbicular as applied to certain granites and diorites.