NMSE, or normalized mean squared error, is a statistical measure used to evaluate the accuracy of a model's predictions or forecasts. Some of the commonly used synonyms for NMSE include normalized root mean square error (NRMSE), root mean square error (RMSE), and mean squared error (MSE). RMSE is particularly useful when comparing different models, while MSE is a standardized way of measuring the estimation error. Other synonyms for NMSE include the coefficient of determination (R-squared), mean absolute error (MAE), and mean percentage error (MPE). Overall, using different synonyms for NMSE can help provide a more comprehensive evaluation of a model's performance.