circumscribed

(mathematics) A closed curve (or surface) is circumscribed about a polygon (or polyhedron) if every vertex of the polygon (or polyhedron) is incident upon the curve (or surface) and the polygon (or polyhedron) is contained in the curve (or surface). A polygon (or polyhedron) is circumscribed about a closed curve (or surface) if every side of the polygon (or face of the polyhedron) is tangent to the curve (or surface) and the curve (or surface) is contained within the polygon (or polyhedron).

Bounded by a line; limited or confined.

The adjective has 2 meanings:

Meaning #1: subject to limits or subjected to limits
  Synonym: limited

Meaning #2: showing or determining a boundary
  Synonym: delimited