noun
boundary; border; precinct; grounds
Refers to the physical or conceptual limits of an area, such as a territory, property, or domain. Somewhat formal or literary.
その川が二つの国の境域となっている。
The river forms the boundary between the two countries.
寺の境域内では静かにしてください。
Please be quiet within the temple precincts.
Compound of 境 (boundary) and 域 (area, region). The reading is on'yomi.