the territory belonging to a town or a people: its district, the land lying inside its recognized limits
This word is built from the Greek word for a boundary, and in the New Testament it always shows up in the plural: literally "the boundaries of" somewhere. Greek used that plural as a shorthand for everything the boundaries hold, so "the boundaries of Judea" is simply the district of Judea, the land that counts as Judea. A more general word for land or open country (χώρα) can cover much of the same ground, but without the idea of set limits.
In practice the word names an area by saying whose it is:
- the country around a city, as in the district of Tyre or of Magadan
- the land of a whole province or tribal area, as in the district of Judea or of Zebulun and Naphtali
- the countryside belonging to a single town, as in Bethlehem and everything around it
- the territory a community governs and can expel an unwelcome visitor from
That last use is the sharpest. When the word takes "their," it carries the weight of who is in charge: the people of the Gadarene district ask Jesus to leave their territory, and the leading citizens of Antioch drive Paul and Barnabas out of theirs. The word marks the edge of what a community can control.
The habit came into the New Testament from the Greek Old Testament, where this is the standard way to render the Hebrew word for a border or a holding (גְּבוּל). That Hebrew word can also mean the boundary stone itself, the marker a dishonest neighbor might quietly move. This Greek word never does that in the New Testament. It is always the land, never the line, and Greek kept a separate term for a boundary that is fixed and appointed (ὁροθεσία).