Usually, bounds. limit or boundary

the bounds of space and time; within the bounds of his estate; within the bounds of reason.

something that limits, confines, or restrains.

bounds,

territories on or near a boundary.

land within boundary lines.

Mathematics . a number greater than or equal to, or less than or equal to, all the numbers in a given set. Compare greatest lower bound , least upper bound , lower bound , upper bound .

to limit by or as if by bounds; keep within limits or confines.

to form the boundary or limit of.

to name or list the boundaries of.

to abut. ?

out of bounds

beyond the official boundaries, prescribed limits, or restricted area

The ball bounced out of bounds.

forbidden; prohibited

The park is out of bounds to students.