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

New York City is forecast to pick up around 2 to 5 inches of snow, sitting right along the boundary of heavy snow to the north and much lesser amounts to the south. —Nadine El-Bawab, ABC News, 8 Feb. 2025

Mysterious land purchases within Joshua Tree National Park worry locals and environmentalists People with ties to the hotel industry are among the buyers and entities that have snapped up 22 parcels within the national park’s boundaries. —Kevinisha Walker, Los Angeles Times, 8 Feb. 2025

Sergio Hudson is unafraid to push the boundaries associated with womenswear. —Robyn Mowatt, Essence, 8 Feb. 2025

Sitting near the boundary of the massive African and Eurasian tectonic plates, Santorini often experiences seismic activity, but rarely so intensely for so long. —Sophie Tanno, CNN, 7 Feb. 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