the process of returning part of the output of a circuit, system, or device to the input, either to oppose the input (negative feedback) or to aid the input (positive feedback)
the furnishing of data concerning the operation or output of a machine to an automatic control device or to the machine itself, so that subsequent or ongoing operations of the machine can be altered or corrected.
a reaction or response to a particular process or activity: He got very little feedback from his speech.
evaluative information derived from such a reaction or response: to study the feedback from an audience survey.
Psychology. knowledge of the results of any behavior, considered as influencing or modifying further performance. Compare biofeedback.
Biology. a self-regulatory biological system, as in the synthesis of some hormones, in which the output or response affects the input, either positively or negatively.

1915–20; noun use of verb phrase feed back Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
feedback (ˈfiːdˌbæk)
1.  a.  the return of part of the output of an electronic circuit, device, or mechanical system to its input, so modifying its characteristics. In negative feedback a rise in output energy reduces the input energy; in positive feedback an increase in output energy reinforces the input energy
 b.  that part of the output signal fed back into the input
2.  the return of part of the sound output by a loudspeaker to the microphone or pick-up so that a high-pitched whistle is produced
3.  the whistling noise so produced
4.  a.  the effect of the product of a biological pathway on the rate of an earlier step in that pathway
 b.  the substance or reaction causing such an effect, such as the release of a hormone in a biochemical pathway
5.  information in response to an inquiry, experiment, etc: there was little feedback from our questionnaire
vb, —adv
6.  (tr) to return (part of the output of a system) to its input
7.  to offer or suggest (information, ideas, etc) in reaction to an inquiry, experiment, etc

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

1920, in the electronics sense, from feed + back (adj.). Transferred use, information about the results of a process is attested by 1955.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

feedback feed·back (fēd'bāk')

  1. The return of a portion of the output of a process or system to the input, especially when used to maintain performance or to control a system or process.

  2. The portion of the output so returned.

  3. The return of information about the result of a process or activity.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
feedback  [%PREMIUM_LINK%]     (fēd'bāk')  Pronunciation Key 
The supply of an input to some process or system as a function of its output. See more at negative feedback, positive feedback.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary

feedback definition

A process in which a system regulates itself by monitoring its own output. That is, it “feeds back” part of its output to itself. Feedback is used to control machines; a heating system, for example, uses a thermostat to monitor and adjust its output. Feedback is also used by the human brain to control various muscles and joints.

Note: By extension, “feedback” is any response or information about the result of a process.
Note: Feedback is usually a feature of automation.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Computing Dictionary

feedback definition

Part of a system output presented at its input. Feedback may be unintended. When used as a design feature, the output is usually transformed by passive components which attenuate it in some manner; the result is then presented at the system input.
Feedback is positive or negative, depending on the sign with which a positive change in the original input reappears after transformation. Negative feedback was invented by Black to stabilise vacuum tube amplifiers. The behaviour becomes largely a function of the feedback transformation and only minimally a function of factors such as transistor gain which are imperfectly known.
Positive feedback can lead to instability; it finds wide application in the construction of oscillators.
Feedback can be used to control a system, as in feedback control.

The Free On-line Dictionary of Computing, © Denis Howe 2010
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Encyclopedia Britannica


in biology, a response within a system (molecule, cell, organism, or population) that influences the continued activity or productivity of that system. In essence, it is the control of a biological reaction by the end products of that reaction.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
We're working to solve these problems, and your feedback will help us do so.
Positive feedback and multiple equilibria have to be taken seriously.
His playing isn't prone to feedback or scrabbling, and he has little interest
  in being the loudest member of the band.
As the systems people would say, there is no feedback loop.
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