Johnson-Nyquist noise, also known as thermal noise, is a fundamental type of noise that occurs in electronic systems and is caused by the random motion of electrons due to thermal energy. There are several synonyms for Johnson-Nyquist noise, such as thermal noise, white noise, Gaussian noise, or thermal agitation noise. The term thermal noise implies that the noise is caused by the thermal energy in a system. The term white noise suggests that the noise power spectrum is flat across all frequencies, and the term Gaussian noise implies that the amplitude distribution of the noise follows a Gaussian distribution. Overall, these synonyms describe the same type of noise that is present in all electronic devices and can be mitigated through proper circuit design and noise reduction techniques.