
In geometry, facetting (also spelled 'faceting') is the process of removing parts of a polygon, polyhedron or polytope, without creating any new vertices.
Facetting is the reciprocal or dual process to stellation. For every stellation of some convex polytope, there exists a dual facetting of the dual polytope.
For example the stellated dodecahedron and great icosahedron'' are two facettings of the icosahedron:
icosahedron  small stellated dodecahedron  great icosahedron 

Facetting has not been studied as extensively as stellation.