the outermost or farthest region or point

the boundary in ancient times between Italy and Gaul; Caesar's crossing it with his army in 49 BC was an act of war

the boundary between the Earth's crust and the underlying mantle

place limits on (extent or amount or access)

form the boundary of; be contiguous to

the natural margin formed by hair on the head

an international boundary or the area (often fortified) immediately inside the boundary

the boundary marking the edge of the sun's influence; the boundary (roughly 100 AU from the sun) between the interplanetary medium and the interstellar medium; where the solar wind from the sun and the radiation from other stars meet

a line that indicates a boundary

an archaic term for a boundary

the boundary in ancient times between Italy and Gaul; Caesar's crossing it with his army in 49 BC was an act of war

the boundary between the Earth's crust and the underlying mantle