From Computer History Wiki
Scope is a term which has a number of meanings in the world of information systemw.
Most formally, in a programming language, it is the range in a program over which a particular variable is visible/usable.
For instance, local variables in an inner block can only be used in that block.
A global variable is one which can be seen, and used, anywhere; in programming languages which allow separately compiled modules to be joined together with a linker after the compilation, a global variable created in one could be seen/used in any part of the linked program.
In a communication network, a scope means a subset of the network, one inside a boundary which selects a portion of the entire network.