In 3 dimensions a polyhedron is defined as a bounded region of space where its boundaries are flat surfaces.

A polyhedron in higher dimensions is often as an intersection of Half-spaces (which can be bounded or unbounded). In this case, a Polytope is defined as a bounded polyhedron. ( https://www.wikiwand.com/en/Polyhedron#/Higher-dimensional_polyhedra )

https://polyhedra.tessera.li/

https://github.com/tesseralis/polyhedra-viewer

https://twitter.com/panlepan/status/947349964375711750

Nice visual and comprehensive collection of polyhedra

how to make every sctrictly convex deltahedron