regressio

Regressio is a Latin noun meaning a return or backsliding; in modern scientific usage it is encountered as the cognate of the term regression. The word derives from regredior “to go back,” formed with the prefix re- “back” and gradior “to step.” In many languages that borrow the term, regressio serves as a general label for processes that move backward or revert to an earlier state.

In psychology, regression denotes a defense mechanism in which an individual temporarily reverts to behaviors characteristic of an earlier developmental period under stress. In medicine, regression can describe the reduction in size or severity of a disease manifestation, such as tumor regression or symptom regression. In statistics and data analysis, regression is a method for modeling the relationship between a dependent variable and one or more independent variables; when expressed in Latin-language texts, this concept may be rendered as regressio or regresso.

Historically, the sense of regressio in classical Latin encompassed return or retreat. The modern technical sense in science developed with the broader adoption of the English term regression in scholarly writing during the 18th to 20th centuries, often via loan translations or direct usage in Latin or vernacular texts.

Related terms include regression, regression analysis, and regression toward the mean.