negative feedback

Short definition from Wiktionary

Noun

1. 1
   A situation where some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances.
2. 2
   A situation where some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances: A feedback loop in which the output signal of a system is amplified with a net negative gain and added to the input signal, before the main amplifier.