demilitarized zone

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An area from which military forces, operations, and installations are prohibited.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An area, often on a border between military factions, in which military forces and operations are prohibited
• noun computing A subnetwork of a LAN, exposed to the internet or another untrusted network but firewalled off from the rest of the LAN.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a zone from which military forces or operations or installations are prohibited