octahedral

[ ok-tuh-hee-druh l ]

/ ˌɒk təˈhi drəl /

having the form of an octahedron.

Origin of octahedral

First recorded in 1750–60; octahedr(on) + -al¹

Both "octahedron / octahedral" and "octohedron / octohedral" occur and have not been changed.

A Guide to the Mount's Bay and the Land's End |John Ayrton Paris
Brass was decomposed, and its constituent copper crystallized in cubic and octahedral forms aggregated in beautiful branches.

The San Francisco Calamity |Various
Sulphur exists in two well-known crystalline forms—rhombic, or octahedral, and monoclinic, or prismatic sulphur.

The Phase Rule and Its Applications |Alexander Findlay
The octahedral cleavage of the diamond is taken advantage of in dressing the stone before cutting it.

Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5 |Various

octahedral

/ (ˌɒktəˈhiːdrəl) /

having eight plane surfaces

shaped like an octahedron