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.

Ball, W. W. R. and Coxeter, H. S. M. Mathematical
Recreations and Essays, 13th ed. New York: Dover, 1987.Coxeter,
H. S. M. and Greitzer, S. L. "Dilation." §4.7 in Geometry
Revisited. Washington, DC: Math. Assoc. Amer., pp. 94-95, 1967.Hilbert,
D. and Cohn-Vossen, S. Geometry
and the Imagination. New York: Chelsea, p. 13, 1999.Stott,
A. B. "Geometrical Deduction of Semiregular from Regular Polytopes and
Space Fillings." Verhandelingen der Koninklijke Akad. Wetenschappen Amsterdam11,
3-24, 1910.