According to Dictionary.com, a moving coil galvanometer is a galvanometer that is operated by an electric current flowing in a movable coil that is suspended in a magnetic field. A galvanometer is an instrument used to detect the existence of small electric currents and determine their strength.
The galvanometer was once referred to as the moving coil electric current detector. If an electric current is present, it passes through the coil of the galvanometer and the coil experiences a torque proportionate to this current. This mechanism is most accurate when the magnetic field that suspends the coil is uniform and constant.