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

• limit
• limitation
• confines
• line

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

Enable agents to dynamically enforce data boundaries so each action stays within the requestor’s entitlements, and embed these capabilities into governance policies and enforcement points. —Ganesh Kirti, Forbes.com, 21 Aug. 2025

And as the music industry continues to not only grow but expand its boundaries beyond one genre or one outlet, entertainment numbers overall are also seeing double-digit increases in industries like film and video production. —Melonee Hurt, The Tennessean, 21 Aug. 2025

The boundaries are not a perfect square but run from 43rd Avenue on the east to 63rd Avenue on the west, and from Camelback Road on the north to McDowell Road on the south. —Erick Trevino, AZCentral.com, 21 Aug. 2025

Be aware of sudden re-direction of fires in response to passing outflow boundaries. —Ca Weather Bot, Sacbee.com, 21 Aug. 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