Real Dictionary

feedback in American English
the transfer of part of the output of an active circuit or device back to the input, either as an unwanted effect or in an intentional use, as to reduce distortion
noun: 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)

feedback in British English
to return (part of the output of a system) to its input
noun: 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 energ

feedback in Electrical Engineering
noun: Feedback is the process of part of the signal coming out of a piece of electrical equipment going back into it to reduce or increase the amplification.

feedback in Mechanical Engineering
noun: Feedback is a type of control in which the error is considered when deciding future control actions.