The meaning of BOUNDARY is something that indicates or fixes a limit or extent. How to use boundary in a sentence.

BOUNDARY definition: a line or limit where one thing ends and another begins, or something that indicates such a line or limit. See examples of boundary used in a sentence.

BOUNDARY definition: 1. a real or imagined line that marks the edge or limit of something: 2. the limit of a subject or…. Learn more.

A boundary is a border and it can be physical, such as a fence between two properties, or abstract, such as a moral boundary that society decides it is wrong to cross.

boundary A line that delineates surface areas for the purpose of facilitating coordination and deconfliction of operations between adjacent units, formations, or areas.

something that indicates bounds or limits, as a line: A mountain range forms a natural boundary between the two countries.

Feb 12, 2026 · Noun boundary (plural boundaries) The dividing line or location between two areas.

A boundary refers to a line, point or plane that marks the limit or edge of something or separates one thing from another such as concepts, objects, territories, or phenomena.

There is a boundary (a circle) isolating the interior of a disc from its exterior. There is a boundary (a surface) enclosing the bulk of this apple. Sometimes the exact location of a boundary is unclear or …

Definition of boundary noun in Oxford Advanced American Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.