boundary

noun bound·ary \ ˈbau̇n-d(ə-)rē \

Updated on: 3 Dec 2017

Definition of boundary

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

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boundaryless

play \-ləs\ adjective

—

boundarylessness

noun

See boundary defined for English-language learners

See boundary defined for kids

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 of boundary from the Web

The ScanPyramid researchers plan to continue to gather data about the mysterious space, further refining its shape and boundaries.

— maya wei-haas, Smithsonian, "How Researchers Uncovered a Massive Void In The Great Pyramid of Giza," 3 Nov. 2017
The first phase of the renovation initially included shifting a back wall to create more space between the playing surface and any physical boundaries as a safety measure.

— USA TODAY, "Updated Neyland renovation project clears first hurdle," 2 Nov. 2017
Better understanding the likelihood of tsunami-generating earthquakes on the offshore plate boundaries is critically important.

— lizzie wade, Science | AAAS, "Underwater network hunts for mysterious slow quakes," 1 Nov. 2017
In a relationship, privacy is about respecting boundaries, honoring how much someone is willing to let down their walls and reveal themselves.

— tracy strauss, Glamour, "My Best Friend Didn't Tell Me About Her Cancer Diagnosis—Then She Died," 25 Oct. 2017
Today, her economic and cultural and military power greater than any in the world, do the leaders and elites of the United States possess the will to deter her enemies from transgressing boundaries and violating national sovereignty?

— matthew continetti, National Review, "What We Can Learn from World War II," 21 Oct. 2017
Peyton Ramsey was sacked twice, Simmie Cobbs was almost completely isolated on the boundaries and the Hoosiers struggled with Michigan’s ultra-athletic defense.

— zach osterman, The Courier-Journal, "3 reasons IU football lost to Michigan Wolverines, 27-20," 14 Oct. 2017
But taken down to its coldest levels, a helium-4 superfluid knows no frictional boundaries.

— david grossman, Popular Mechanics, "The Quest for Absolute Zero Turns Up Strange and Surreal Superfluids," 12 Oct. 2017
Women are responsible for drawing up those boundaries, and if men overstep them, that’s not their fault: boys will be boys.

— laurie penny, Longreads, "The Horizon of Desire," 11 Oct. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'boundary.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of boundary

²bound + ¹-ary

NEW! Time Traveler

First Known Use: 1598

See Words from the same year

boundary Synonyms

Synonyms

bound, limit, cap, ceiling, confines, end, extent, limitation, line, termination

Related Words

extremity, fag end, terminus; border, brim, edge, margin, rim, verge; outside; bar, barrier, fence, hedge, restraint, stop, wall

Near Antonyms

center, core, heart; inner, inside, interior, middle, within

BOUNDARY Defined for English Language Learners

boundary

noun

Definition of boundary for English Language Learners

: something (such as a river, a fence, or an imaginary line) that shows where an area ends and another area begins
: a point or limit that indicates where two things become different
boundaries : unofficial rules about what should not be done : limits that define acceptable behavior