[power supply design] Foldback is a current limiting feature (a type of overload protection) of power supplies and power amplifiers. When the load attempts to draw overcurrent from the supply, foldback reduces both the output voltage and current to well below the normal operating limits. Under a short circuit, where the output voltage has r...[sound engineering] Foldback is the use of rear-facing loudspeakers known as monitor speakers or stage monitors on stage during live music performances. The sound is amplified with power amplifiers or a public address system and the speakers are aimed at the on-stage performers rather than the audience. This sound signal may be produced on ...
in Britain, this is the term for an onstage monitor speaker that helps performers to hear their singing and playing.
A European term for the signal sent to the stage monitors in a live performance.
Sound reinforcement from loudspeakers on the side of the stage to enable actors to hear their musical accompaniments clearly, and to hear their own voices when the sound is heavily reinforced for the audience. 
This is an audio feed sent to the performer using speakers or headphones to allow them to monitor the sounds they are producing.
System for feeding one or more separate mixes to the performers for use while recording and overdubbing. Also known as a Cue mix.
in Britain, this is the term for an onstage monitor speaker that helps performers to hear their singing and playing.
The process of returning the amplified sound to the stage so that the performers can hear themselves. Rarely used in straight plays: essential for musical work of all kinds. Special foldback monitors are needed which much less likely to feed into the mics to produce feedback (qv).