boundary

noun

bound·​ary ˈbau̇n-d(ə-)rē 

plural boundaries

: something that indicates or fixes a limit or extent

Those two trees mark the boundary of our property.

the mountain range that forms the country's northern boundary

boundaryless

ˈbau̇n-d(ə-)rē-ləs 

adjective

boundarylessness noun

Synonyms

• bound
• cap
• ceiling
• confines
• end
• extent
• limit
• limitation
• line
• termination

Examples of boundary in a Sentence

Those two trees mark the boundary of our property.

The river forms the country's western boundary.

at the boundary between fact and fiction

You need to set boundaries with your children.

Did he violate the boundaries of the doctor-patient relationship?

Recent Examples on the Web

Lamm is responsible for Chaotic Moon Studios, a software design and development company that pushed the boundaries of digital experiences. —Ron Estes, MSNBC Newsweek, 29 Mar. 2025

The work radiates a rare curiosity and playfulness, slipping between the boundaries of literature, performance, and archaeology. —Matthew Carey, Deadline, 29 Mar. 2025

The Multi-Platform Transmedia Imperative As traditional media boundaries continue to blur, companies that can successfully navigate the complexities of transmedia adaptation stand to capture significant market share in the global entertainment landscape. —Damion Taylor, Forbes.com, 28 Mar. 2025

The best tiny house rentals are a neat way to explore boundaries of space with a special someone or have an adventurous getaway on a budget. —Kristi Kellogg, Architectural Digest, 28 Mar. 2025

Word History

Etymology

bound entry 6 + -ary entry 1

First Known Use

1598, in the meaning defined above

Phrases Containing boundary

• boundary layer
• K-T boundary

Kids Definition

boundary

noun

bound·​ary ˈbau̇n-d(ə-)rē 

plural boundaries

: something that points out or shows a limit or end : dividing line

Legal Definition

boundary

noun

bound·​ary

plural boundaries

: a theoretical line that marks the limit of an area of land