Cantellation, also known as (polyhedron) expansion (Stott 1910, not to be confused with general geometric expansion) is the process of radially displacing the edges or faces of a polyhedron while keeping their orientations and sizes constant then filling in the gaps with new faces (Ball and Coxeter 1987, pp. 139-140). This procedure was devised by Stott (1910), and can be used to construct all 11 amphichiral (out of 13 total) Archimedean solids. The opposite operation of polyhedron expansion (i.e., inward expansion) can ne called polyhedron contraction. Expansion is a special case of snubification in which no twist occurs.
The term "cantellation" is sometimes reserved for the 
-dimensional version of the operation corresponding to polyhedron
expansion.
The following table summarizes some expansions of some unit edge length Platonic and Archimedean solids, where 
is the displacement and 
is the golden ratio.
