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

Starlink’s global nature pushes the boundaries of traditional regulatory frameworks. —Tim Bajarin, Forbes, 18 Mar. 2025

The difference is that behaviors happen in a supportive environment where boundaries are held while children feel heard and validated. —Adrianna Rodriguez, USA TODAY, 18 Mar. 2025

The brand said the work is designed to bridge the legacy of rare craft practices passed down through generations at The Balvenie with a contemporary lens, creating an experience that hopes to redefine the boundaries of hospitality and design. —Tianwei Zhang, WWD, 18 Mar. 2025

With that, Roth is quick to credit friends and fellow scare-mongers at the top of the 2000s such as Rob Zombie, James Wan and Darren Bousman for pushing the boundaries of guts, gore and terror. —A.d. Amorosi, Variety, 18 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