boundary

[boun-duh-ree, -dree]

noun

plural

boundaries 

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.

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 Word Forms

• transboundary 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

The 37-year-old Kohli remained the hero with his 83rd ton across the three international formats after he raised his hundred with a boundary off Jansen and lifted his bat to a raucous home crowd.

Read more on Barron's

"A text that is not about political boundaries in a modern sense became an instance of God's ordering of the world according to nation-states."

Read more on Science Daily

Revealing a boundary as fragile as this paper-thin clay layer required painstaking work.

Read more on Science Daily

Still, commercial pressures motivate shippers to push boundaries, raising the risk of accidents, oil spills or getting stuck in ice.

Read more on The Wall Street Journal

A general licence is available that allows animals to cross the boundary if they are going directly to slaughter.

Read more on BBC

Related Words

• barrier 
• border 
• borderline 
• confines www.thesaurus.com
• edge 
• frontier 
• horizon 
• line 
• perimeter