1. (sometimes caps.) a barrier to understanding and the exchange of information and ideas created by ideological, political, and military hostility of one country toward another, esp. such a barrier between the Soviet Union and its allies and other countries.
2. an impenetrable barrier to communication or information, esp. as imposed by rigid censorship and secrecy.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.