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

Since emotional labor often lacks clear boundaries, the habit of providing extensive context and reassurance can extend across both personal and professional settings. —Mark Travers, Forbes, 6 Mar. 2025

The source also doubled down about how the couple and Ben put up strict boundaries with each other. —Lea Veloso, StyleCaster, 6 Mar. 2025

Launching Last Word Entertainment is about that same drive: pushing boundaries, uncovering the untold and telling stories that demand to be heard. —Jesse Whittock, Deadline, 5 Mar. 2025

His vision redefined electronic music, pushing boundaries and reshaping the industry. —Jem Aswad, Variety, 5 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