1. The portion of electronic jamming that is directed against communications circuits and systems.
2. The prevention of successful radio communications by the use of electromagnetic signals, i.e., the deliberate radiation, reradiation, or reflection of electromagnetic energy with the objective of impairing the effective use of electronic communications systems.
Note: The aim of communications jamming is to prevent communications by electromagnetic means, or at least to degrade communications sufficiently to cause delays in transmission and reception. Jamming may be used in conjunction with deception to achieve an overall electronic-countermeasure (ECM) plan implementation.
Source: from Federal Standard 1037C