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

Mueller echoed this sentiment, noting that tequila’s popularity will allow producers to explore the boundaries of the spirit. —Rachel King, Forbes, 5 Jan. 2025

View 5 Images Trust a Chinese automaker to consistently push the boundaries of innovation. —New Atlas, 5 Jan. 2025

The team finds that there are two major sources of molten material that extend up from the mantle-crust boundary at about 50 kilometers below the surface. —Ars Technica, 3 Jan. 2025

Trusting people doesn’t mean never setting boundaries or never asking that accommodations be made for a child who needs them. —Stephanie H. Murray, The Atlantic, 2 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