oc·ta·he·dron / ˌäktəˈhēdrən/ • n. (pl. -drons or -dra / -drə/ ) a three-dimensional shape having eight plane faces, esp. a regular solid figure with eight equal triangular faces. ∎  a body, esp. a crystal, in the form of a regular octahedron.DERIVATIVES: oc·ta·he·dral / -drəl/ adj.

octahedron

octahedron A three-dimensional, eight-sided form in which all the faces are equilateral triangles (i.e. it resembles a double pyramid). In crystallography, a crystal form in which the crystal faces cut all three crystallographic axes at equal distances.