The Collaborative International Dictionary
three-mile zone
Three-mile \Three"-mile`\, a. Of or pertaining to three miles; as,
the three-mile limit, or the limit of the marine belt (the
three-mile belt or three-mile zone) of three miles included in territorial waters (which see) of a state.
Usage examples of "three-mile zone".
In a matter of moments she was beyond the three-mile zone and into the waters of no man's land.