The bounds within which a thing applies. Scope is what keeps a rule from reaching where it was not meant to.
Greek skopos (a target, a watcher), from skeptesthai (to look at, examine); scope names the bounds a rule is aimed at, from the same root that gives telescope and microscope their looking.
The bounds within which a rule is meant to reach — what keeps a rule aimed at what it was made for, rather than drifting wherever it can.