(logic) A regress into an infinite sequence of propositions in an attempt to found the truth of the proposition Pᵢ on the truth of the proposition Pᵢ₊₁.

(philosophy) The paradoxical situation whereby, if one accepts the cognitivist theory that every action is preceded by a thought, each thought must also be preceded by another thought, and so thinking could apparently never begin.

(derogatory, politics) A characterization of the left which suggests that it paradoxically holds reactionary views by its tolerance of illiberal principles and ideologies (such as extremist Islamism) for the sake of multiculturalism and cultural relativism.

(software engineering) Testing a program after a modification to ensure that areas that should not be affected by the update behave as they did in previous versions.

(phonetics, phonology) An assimilation whereby a sound becomes more like the following sound.

plural of regressive assimilation

plural of regression tree

plural of regression to the mean

(derogatory, politics, rare) The politics of the regressive left.

Mental reversion to a younger age, used in therapy, as a coping mechanism, or as a manifestation of a psychiatric issue.