• synonyms


[boun-duh-ree, -dree]
See more synonyms for boundary on Thesaurus.com
noun, plural bound·a·ries.
  1. something that indicates bounds or limits; a limiting or bounding line.
  2. Also called frontier. Mathematics. the collection of all points of a given set having the property that every neighborhood of each point contains points in the set and in the complement of the set.
  3. Cricket. a hit in which the ball reaches or crosses the boundary line of the field on one or more bounces, counting four runs for the batsman.Compare six(def 5).
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Origin of boundary

First recorded in 1620–30; bound3 + -ary
Related formstrans·bound·a·ry, adjective
Can be confusedboundary limit parameter variable

Synonym study

1. Boundary, border, frontier share the sense of that which divides one entity or political unit from another. Boundary, in reference to a country, city, state, territory, or the like, most often designates a line on a map: boundaries are shown in red. Occasionally, it also refers to a physical feature that marks the agreed-upon line separating two political units: The Niagara River forms part of the boundary between the United States and Canada. Border is more often used than boundary in direct reference to a political dividing line; it may also refer to the region (of, for instance, a country) adjoining the actual line of demarcation: crossing the Mexican border; border towns along the Rio Grande. Frontier may refer to a political dividing line: crossed the Spanish frontier on Tuesday. It may also denote or describe the portion of a country adjoining its border with another country ( towns in the Polish frontier ) or, especially in North America, the most remote settled or occupied parts of a country: the frontier towns of the Great Plains. Frontier, especially in the plural, also refers to the most advanced or newest activities in an area of knowledge or practice: the frontiers of nuclear medicine.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for boundary

perimeter, barrier, borderline, frontier, confines, edge, horizon, line, border, frame, circumscription, rim, radius, verge, mete, pale, brink, borderland, ambit

Examples from the Web for boundary

Contemporary Examples of boundary

Historical Examples of boundary

  • They are like explorers who should mistake a boundary for the interior of a continent.

    Bride of the Mistletoe

    James Lane Allen

  • They are crossing the boundary between the first childhood and the second.

    Bride of the Mistletoe

    James Lane Allen

  • The seventh of these hath a bough which shoots over the boundary wall.

    Micah Clarke

    Arthur Conan Doyle

  • Right ahead was a stone marker which he knew marked the boundary of 150 Nevada.

    Louisiana Lou

    William West Winter

  • The misfortune then was that no boundary stones could be found.


    Emile Zola

British Dictionary definitions for boundary


noun plural -ries
  1. something that indicates the farthest limit, as of an area; border
  2. cricket
    1. the marked limit of the playing area
    2. a stroke that hits the ball beyond this limit
    3. the four runs scored with such a stroke, or the six runs if the ball crosses the boundary without touching the ground
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for boundary


1620s, from bound (n.) + -ary.

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Online Etymology Dictionary, © 2010 Douglas Harper