regression

(noun) an abnormal state in which development has stopped prematurely. Synonyms: arrested development, fixation, infantile fixation.

(noun) (psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state.

(noun) 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). Synonyms: simple regression, regression toward the mean, statistical regression.

(noun) returning to a former state. Synonyms: regress, reversion, retrogression, retroversion.