a. [ See octahedron. ] Having eight faces or sides; of, pertaining to, or formed in, octahedrons; as, octahedral cleavage; an octahedral crystal. [ 1913 Webster ]

octahedral borax (Chem.), borax obtained from a saturated solution in octahedral crystals, which contain five molecules of water of crystallization; distinguished from common or prismatic borax. --
Octahedral iron ore (Min.), magnetite. [ 1913 Webster ]