definitions
• synonyms

# boundary

[boun-duh-ree, -dree]
See more synonyms 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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First recorded in 1620–30; bound3 + -ary
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
British Dictionary definitions for transboundary

# 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
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

# boundary

### n.

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

Online Etymology Dictionary, © 2010 Douglas Harper