stellated

Stellated is an adjective used chiefly in geometry to describe figures that have been formed by stellation, a process in which the faces or edges of a polygon or polyhedron are extended beyond their initial boundaries until they intersect to form a new, often star-shaped surface. The result is a stellated figure or solid.

In two dimensions, stellation can be applied to polygons by extending their sides until they meet to create star polygons. The most familiar example is the pentagram, formed by continuing the sides of a regular pentagon. In three dimensions, stellation extends the planes of a convex polyhedron; the extensions intersect to define a new outer surface, yielding a stellated polyhedron.

Two famous stellated polyhedra are the small stellated dodecahedron and the great stellated dodecahedron, both classified among the Kepler-Poinsot solids. They arise from extending the faces of a dodecahedron, resulting in non-convex, star-like forms with intricate symmetry. These solids are studied in polyhedral theory and have historical significance in the exploration of regularity and symmetry beyond convex shapes.

The term stellation is one method of constructing or describing geometric forms and is sometimes used more broadly to denote star-shaped or star-like features in other contexts, including ornamentation and natural forms. The root stems from Latin stellatus, meaning star-shaped.