boundary, bounds, bound - the line or plane indicating the limit or extent of something

fence line - a boundary line created by a fence

Green Line - the border marking the boundaries of the land that Israel won in its 1948 war of independence

Line of Control - a 450-mile line that is supposed to indicate the boundary between the part of Kashmir controlled by India and the part controlled by Pakistan

property line - the boundary line between two pieces of property

state boundary, state line - the boundary between two states