Critical assessment of a process or activity or of their results.

(electronics, cybernetics, control theory) The part of an output signal that is looped back into the input to control or modify a system.

(amplification) The high-pitched howling noise heard when there is a loop between a microphone and a speaker.

(music) To generate the high-frequency sound by allowing a speaker to cause vibration of the sound generator of a musical instrument connected by an amplifier to the speaker.

(transitive) To provide informational feedback to.

(transitive) To convey by means of specialized communications channel.