boundary

[ boun-duh-ree, -dree ]

noun

, plural bound·a·ries.

1. a line or limit where one thing ends and another begins, or something that indicates such a line or limit:

   The ancient wall still serves as the city's outer boundary.

   These studies straddle the boundaries between computational and social sciences.

   Synonyms: limit, bound

2. a limit that separates acceptable behavior from unacceptable behavior:

   I'm just looking for a partner who can respect my boundaries.

   Guiding children toward responsible money habits requires setting boundaries.

3. 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.
4. 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 ).

boundary

/ -drɪ; ˈbaʊndərɪ /

noun

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

Other Words From

• trans·bound·a·ry adjective

Word History and Origins

Origin of boundary¹

First recorded in 1620–30; bound ³ + -ary

Synonym Study

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.

Example Sentences

Israeli afforestation is not limited to the state's internationally recognized boundaries.

From Salon

In atmospheric science, the boundary layer of the atmosphere is the region closest to the Earth's surface.

From Science Daily

While it's important to validate feelings, she says, parents should also set clear boundaries on aggressive behavior like hurting others or breaking things.

From Science Daily

A Unifil spokesman in Geneva said UN peacekeepers were seeing increased levels of violence, with "huge, shocking" destruction across the blue line - the UN-recognised boundary that separates Israel and Lebanon.

From BBC

However, California’s emphasis on such liberal issues pushes the boundaries for many moderate voters, even those who may be sympathetic to some progressive polices, Kochel said.

From Los Angeles Times

Related Words

• barrier
• border
• borderline
• bounds
• confines
• edge
• frontier
• horizon
• line
• perimeter