1. A division of electronic warfare in which actions are taken to interfere with a military enemy's use of the electromagnetic or a range of electromagnetic radiation or waves, used in military air defenses and interceptions.
2. The disruption of the operation of a military enemy's equipment; as by jamming radio or radar signals.
3. A military offensive or defensive tactic or device using electronic and reflecting apparatuses (apparatus or systems allowing certain functions) to reduce the military effectiveness of enemy equipment involving electromagnetic radiation; such as, guidance, radar, communication, or other radio-wave devices.

Reconnaissance by aircraft equipped with electronic devices capable of locating enemy radar stations, determining their area coverage, and making radarscope recordings for combat mission folders.