boundary
n. countablen. a line that marks the edge of an area or the limit of what is allowed. You can use it for physical borders or for rules about how people should treat you.
n. a real or imaginary line that marks the edge or limit of something. Often used metaphorically to describe the limits of acceptable behavior or professional relationships.
The fence marks the boundary between the two gardens.
Setting a clear boundary between work and home life is essential for maintaining your mental health.
The treaty established a new international boundary along the river, though local communities continued to cross the water as they had for centuries before the formal agreement.
From bound + -ary, Old French, from Latin.
Often used with the verbs 'set', 'establish', or 'cross'.