noun
octahedron
A polyhedron with eight faces. Used in geometry and crystallography.
正八面体はプラトンの立体の一つです。
A regular octahedron is one of the Platonic solids.
六面体 is a hexahedron (6 faces), such as a cube.
Compound of 八 (eight), 面 (face), and 体 (body). A straightforward kanji-based term for an eight-faced solid.