regular octahedron(n = noun.shape) - an octahedron with eight equilateral triangles as faces;
is a kind of ideal solid, platonic body, platonic solid, regular convex polyhedron, regular convex solid, regular polyhedron

octahedron, on a regular basis, regular, regular army, regular convex polyhedron, regular convex solid, regular dodecahedron, regular hexagon, regular hexahedron, regular icosahedron, regular payment, regular polygon, regular polyhedron, regular recurrence, regular tetrahedron