A circumscriber is a person or thing that surrounds or encircles something. Synonyms for this word include boundary keeper, confiner, encloser, limiter, and restrictor. Another synonym that can be used interchangeably with circumscriber is delineator, which refers to a person or thing that draws or outlines the boundary or limits of something. Similarly, a defining or demarcating line can serve as a synonym for circumscriber. These words all suggest a sense of defining, enclosing, or limiting something within certain parameters, whether they are physical, conceptual, or organizational.