boundary
- 01 B1 Intermediate
a real or imagined line that marks the edge of a place, like a country or a garden.
a line or border marking the limit of a physical area or territory.
Simple“The river forms a natural boundary between the two farms.”
In context“The surveyors spent weeks marking the exact boundary between the private estate and the newly designated national park.”
- 02 B2 Upper Intermediate
a limit that you set to protect your feelings, privacy, or time.
a metaphorical limit or rule defining acceptable behaviour, privacy, or professional conduct in social interactions.
Simple“It is important to set clear boundaries between your work life and your home life.”
In context“The therapist emphasized the importance of maintaining professional boundaries when dealing with long-term clients to ensure objective care.”
- 03 C1 Advanced
the edge of the playing area in a game like cricket.
the outer limit of a playing field, or a scoring event where the ball crosses this line.
Simple“The batsman hit the ball hard and it flew over the boundary for six runs.”
In context“The fielder made a desperate dive to stop the ball before it reached the boundary, but his effort was just a second too late.”
Usageoften used in the context of cricket to describe a hit that scores four or six runs.
- 04 C2 Proficiency
the set of points on the very edge of a shape or group of numbers.
the set of points in the closure of a set that do not belong to its interior.
Simple“The boundary of the circle is the line that forms its circumference.”
In context“In topology, the boundary of a set is defined as the intersection of the closure of the set and the closure of its complement.”
Usage boundary blur · cross boundary · define pattern boundary
“But it doesn’t feel confrontational; more demarcating well-defined boundaries and a hard-won ability to claim their achievements.”
“I respect Austen’s skill, but I’m drawn to books about characters who cross boundaries, venture into the unknown rather than finding their place within the social order.”
From bound + -ary, Old French, from Latin.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.