Servo-Motor

Part of speech: noun (n.)

1. A relay apparatus; specif.:

2. An auxiliary motor, regulated by a hand lever, for quickly and easily moving the reversing gear of a large marine engine into any desired position indicated by that of the hand lever, which controls the valve of the motor.

3. In a Whitehead torpedo, a compressed-air motor, for moving the rudders so as to correct deviations from the course.