From Citizendium, the Citizens' Compendium
- Signals intelligence : the practice of acquiring information through monitoring the electromagnetic signals deliberately trasmitted by an opponent, including communications (COMINT) and non-communications electronics such as radar (ELINT).
- SIGINT in the Second World War : Add brief definition or description
- : Second World War location of the main British signals intelligence organization, the Government Code and Cipher School
- Bombe : Add brief definition or description
- Enigma machine : The primary high-security cryptographic communications security machine of Nazi Germany. Unknown to the Germans, it had been substantially cryptanalyzed by the British Government Code and Cipher School, with French, Polish, and U.S. help.
- Government Code and Cipher School : World War II cover name for the British signals intelligence organization; now the Government Communications Headquarters