1) The effect of residual magnetism whereby the magnetization of a ferrous substance lags the magnetising force because of molecular friction. 2) The property of magnetic material that causes the magnetic induction for a given magnetising force to depend upon the previous conditions of magnetization. 3) A form of nonlinearity in which the response of a circuit to a particular set of input conditions depends not only on the instantaneous values of those conditions, but also on the immediate past of the input and output signals.