forms of the English definite article in Northern England Philosophy Reductionism, a range of philosophical systems Reductio ad absurdum, a form of argument in which a proposition is disproven by following its implications to an absurd consequence Eidetic reduction, a technique in the study of essences in phenomenology whose goal is to identify the basic components of phenomena Intertheoretic reduction, in philosophy of science, one theory makes predictions that perfectly or almost perfectly match the predictions of a second theory Settlements Reductions, settlements in Spanish America intended to control and Christianize Indians Indian reductions in the Andes, settlements in the Andes to control and Christianize Indians Other uses Reduction (cooking), the process of thickening or intensifying the flavor of a liquid mixture such as a soup, sauce, wine, or juice by evaporation Reduction (military), the siege and capture of a fortified place Reduction (Sweden), a return to the Crown of fiefs that had been granted to the Swedish nobility Reduce (waste), practices of minimizing waste Reduction, Pennsylvania, unincorporated community, United States Reduction in rank, in military law Reduction to practice, in United States patent law, the embodiment of the concept of an invention Ego reduction, predicated on the use of Sigmund Freud's concept of the ego Reductions, resettlement of indigenous peoples during the Spanish colonization of the Americas See also Prevention (disambiguation) Risk reduction (disambiguation) Mathematics disambiguation pages