1. A Short name referring to investigation, study, and control of compromising emanations from information systems (IS) equipment. 2. To shield against compromising emanations. 3. The unintentional radiation or conduction of compromising emanations from communications, non-communications and/or computer systems. See also: Radiation Security. 4. The study and control of spurious electronic signals emitted from ADP equipment. TEMPEST is a standard for electromagnetic shielding for computer and communications equipment. It was created in response to the fact that information may be read from radiation from such devices at a distance.