Boundary

Webster's Dictionary of the English Language

·noun That which indicates or fixes a limit or extent, or marks a bound, as of a territory; a bounding or separating line; a real or imaginary limit.

Related Words

boundary-rider
n. a man who rides round thefences of a station to see that they are in order. 1890. E. W. Hornung...

Dictionary of Australasian Words Phrases and Usages by Edward E. Morris