In telecommunication, the term electromagnetic compatibility (EMC) has the following meanings:
1. Electromagnetic compatibility is the condition which prevails when telecommunications equipment is performing its individually designed function in a common electromagnetic environment without causing or suffering unacceptable degradation due to unintentional electromagnetic interference to or from other equipment in the same environment.
2. The ability of systems, equipment, and devices that utilize the electromagnetic spectrum to operate in their intended operational environments without suffering unacceptable degradation or causing unintentional degradation because of electromagnetic radiation or response. It involves the application of sound electromagnetic spectrum management; system, equipment, and device design configuration that ensures interference-free operation; and clear concepts and doctrines that maximize operational effectiveness.
Source: from Federal Standard 1037C and from the NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management and from the Department of Defense Dictionary of Military and Associated Terms
See also spread spectrum.