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

This thrilling film dives into risk tolerance and personal journeys, showcasing their relentless drive to push boundaries and embrace the wild, even in the face of danger. —Forbes, 17 Jan. 2025

With its focus on pushing boundaries and meeting evolving needs, LiTime remains a beacon of progress in creating a sustainable, energy-independent future for all. —Lauren Carpenter, USA TODAY, 17 Jan. 2025

Fox, who is known for always pushing boundaries with her sartorial sense of style, previously talked with WWD about her relationship with fashion. —Renan Botelho, WWD, 17 Jan. 2025

The 29-year-old woman, who has been caring for her sister’s children for years, recently reached a breaking point and decided to set some boundaries with her sister. —Ashley Vega, People.com, 16 Jan. 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