v. & n.
v. 1 intr. move backwards, esp. (in abstract senses) return to a former state. 2 intr. & tr. Psychol. return or cause to return mentally to a former stage of life, esp. through hypnosis or mental illness.
n. 1 the act or an instance of going back. 2 reasoning from effect to cause.
[ ME (as n.) f. L regressus f. regredi regress- (as RE-, gradi step) ]