boundary
/ ˈbaundəri /

◙ (pl. -ies)
1. a line which marks the limits of an area; a dividing line
• 分界线，边界；界限
»a county boundary.
  县界。
»the river marks the boundary between the two regions.
  这条河是这两个地区的分界线。
»[as modifier] a boundary wall.
  界墙。
  [常作 boundaries] (figurative)a limit of something abstract, especially a subject or sphere of activity
• [喻] （某些抽象事物的）界限
»a community without class or political boundaries.
  一个没有阶级或政治界限的社区。
  [Cricket] a hit crossing the limits of the field, scoring four or six runs
• [板球] 击球到（或超过）边界线得分（得4分和6分）

【语源】

1. early 17th cent.: variant of dialect bounder, from bound + -er,perhaps on the pattern of limitary