octahedrid

octahedrid, a. Cryst.

(ɒktəˈhiːdrɪd, -ˈhɛdrɪd)

[f. as prec. + -id².]

Applied to any plane, in a crystallographic system, which intersects all the three axes of coordinates; so called because a group of eight such planes would form an octahedron. Opposed to prismatoid and pinakoid.

Story-Maskelyne Crystallogr. ii. §18.