fɪksˈeɪʃən ɹiːˈɡɹɛʃən ɹɪˈvɜːʒən returning to a former state the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x) (psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state an abnormal state in which development has stopped prematurely