A Servo Motor is defined as an automatic device that uses an error-correction routine to correct its motion.

The term servo can be applied to systems other than a Servo Motor;Systems that use a feedback mechanism such as an encoder or other feedback device to control the motion parameters.

Typically when the term servo is used it applies to a ‘Servo Motor’ but is also used as a general control term,meaning that a feedback loop is used to position an item.