The term rectification is sometimes used to refer to the determination of the length of a curve.
Rectification also refers to the operation which converts the midpoints of the edges of a regular polyhedron to the vertices of
the related "rectified" polyhedron. Rectified forms are bounded by a combination
of rectified cells and vertex figures. Therefore,
a rectified polychoron 
is bounded by 
s
and 
s.
For example, 
is bounded by 600 truncated tetrahedra (truncated cells) and 120 icosahedra (vertex
figures). A rectified polyhedron is indicated by prepending an "r" to the
Schläfli symbol.
| polyhedron | Schläfli symbol | rectified polyhedron | Schläfli symbol |
| tetrahedron |  | octahedron |  |
| octahedron |  | cuboctahedron |  |
| cube |  | cuboctahedron |  |
| icosahedron |  | icosidodecahedron |  |
| dodecahedron |  | icosidodecahedron |  |
| 16-cell |  | 24-cell |  |
Rectification of the six regular polychora gives five (not six) new polychora since the rectified 16-cell 
is the 24-cell 
.
