Demilitarized Zone (DMZ)

An interface on a routing firewall that is similar to the interfaces found on the firewall’s protected side. Traffic moving between the DMZ and other interfaces on the protected side of the firewall still goes through the firewall and can have firewall protection policies applied.
SOURCE: SP 800-41

A host or network segment inserted as a “neutral zone” between an organization’s private network and the Internet.
SOURCE: SP 800-45

Perimeter network segment that is logically between internal and external networks. Its purpose is to enforce the internal network’s Information Assurance policy for external information exchange and to provide external, untrusted sources with restricted access to releasable information while shielding the internal networks from outside attacks.
SOURCE: CNSSI-4009