Webster's Revised Unabridged Dictionary · 1913

Rhombohedral

Rhombohedral , adjective

(Geometry & Crystallography) 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.
Collocations (2)
Rhombohedral iron ore (Mineralogy) , See Hematite.
Rhombohedral system (Crystallography) , a division of the hexagonal system embracing the rhombohedron, scalenohedron, etc.