1. To draw a line around; encircle.
2. To limit narrowly; restrict.
3. To determine the limits of; define. See synonyms at limit.
4. a. To enclose (a polygon or polyhedron) within a configuration of lines, curves, or surfaces so that every vertex of the enclosed object is incident on the enclosing configuration. b. To erect (such a configuration) around a polygon or polyhedron: circumscribe a circle around a square.