Boundary line and Rails

Boundary line noun - A line that indicates a boundary.

Rails and boundary line are semantically related. In some cases you can use "Rails" instead a noun phrase "Boundary line".

Rails noun - A bar or pair of parallel bars of rolled steel making the railway along which railroad cars or other vehicles can roll.

Boundary line and rails are semantically related. Sometimes you can use "Boundary line" instead a noun "Rails".