1. an arrangement whereby some of the output of a system, whether mechanical or biological, is fed back to reduce the effect of input signals. Such systems, which measure the deviation from a desired state and apply a correction, are important in achieving homeostasis, whereas systems employing positive feedback tend to amplify small deviations and become highly unstable. See feedback system.

2. nonconstructive criticism, disapproval, and other negative information received by a person in response to his or her performance.