Noun

1. An action of regressing, a return to a previous state.
   • 1899: Thorstein Veblen, The Theory of the Leisure Class

     Few of these groups or communities that are classed as "savage" show no traces of regression from a more advanced cultural stage.

2. A psychotherapeutic method whereby healing is facilitated by inducing the patient to act out behaviour typical of an earlier developmental stage.
3. An analytic method to measure the association of one or more independent variables with a dependent variable.
4. An equation using specified and associated data for two or more variables such that one variable can be estimated from the remaining variable(s).