What does "rhombohedral" mean?

Rhombohedral: Related to the rhombohedron; presenting the form of a rhombohedron, or a form derivable from a rhombohedron; relating to a system of forms including the rhombohedron and scalenohedron. Rhombohedral iron ore (Min.) See Hematite. -- Rhombohedral system (Crystallog.), a division of the hexagonal system embracing the rhombohedron, scalenohedron, etc.