An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Geometry: A three-dimensional figure formed by several → polygons.
2) A set P ⊆ ℜⁿ is a polyhedron if there is a system of finitely many unequalities Ax ≤ b such that P = {x ∈ ℜⁿ | Ax ≤ b}.

→ poly-; → hedron.