[ boun-duh-ree, -dree ]
See synonyms for: boundaryboundaries on

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.

  1. 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).

Origin of boundary

First recorded in 1620–30; bound3 + -ary

synonym study For boundary

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.

Other words for boundary

Other words from boundary

  • trans·bound·a·ry, adjective

Words Nearby boundary Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use boundary in a sentence

British Dictionary definitions for boundary


/ (ˈbaʊndərɪ, -drɪ) /

nounplural -ries
  1. something that indicates the farthest limit, as of an area; border

  2. cricket

    • the marked limit of the playing area

    • a stroke that hits the ball beyond this limit

    • the four runs scored with such a stroke, or the six runs if the ball crosses the boundary without touching the ground

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