Expansion is an affine transformation (sometimes called an enlargement or dilation) in which the scale is increased. It is the opposite of a geometric contraction, and is also sometimes called an enlargement. A central dilation corresponds to an expansion plus a translation.
Polyhedron expansion, also known as cantellation is a different type of expansion in which a subset of edges or faces of a polyhedron are radially displaced while keeping their orientations and sizes constant, then filling in the gaps with new faces.
