We investigate a dynamic fuzzy logic system, specifically, its non-singleton generalization, and derive a novel adaptive fuzzy line enhancer that successfully solves the non-linear problem of narrowband interference (NBI) estimation and rejection in DS/CDMA for non-stationary environments. The NBI suppression performance of this method is compared with the performance of the linear and nonlinear estimator-substracter NBI suppression techniques for low and high signal to noise ratios (SNRs). It is seen that the proposed method outperforms all the previous nonlinear methods of NBI suppression whatever the SNR is, while almost attains the good performance of the linear ALE for low SNR and slow varying interference.