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

Because there’s no word for boundaries in Japanese. —J.m. Banks, Kansas City Star, 17 May 2025

Wanting to avoid a repeat of past experiences, the woman decided to set a boundary. —Ashley Vega, People.com, 16 May 2025

Adapt Productivity Expectations Employees have a hard time establishing boundaries for fear of being let go. —Expert Panel®, Forbes.com, 16 May 2025

In addition, the COVID-19 pandemic led many people to renegotiate their comfort with touch and spatial boundaries. —Brian N. Chin, The Conversation, 16 May 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