Cartesian means of or relating to the French philosopher René Descartes—from his Latinized name ''Cartesius''. It may refer to:


*Cartesian closed category, a closed category in category theory *Cartesian coordinate system, modern rectangular coordinate system *Cartesian diagram, a construction in category theory *Cartesian geometry, now more commonly called analytic geometry *Cartesian morphism, formalisation of ''pull-back'' operation in category theory *Cartesian oval, a curve *Cartesian product, a direct product of two sets *Cartesian product of graphs, a binary operation on graphs *Cartesian tree, a binary tree in computer science


*Cartesian anxiety, a hope that studying the world will give us unchangeable knowledge of ourselves and the world *Cartesian circle, a potential mistake in reasoning *Cartesian doubt, a form of methodical skepticism as a basis for philosophical rigor *Cartesian dualism, the philosophy of the distinction between mind and body **Cartesianism, the philosophy of René Descartes **Cartesianists, followers of Cartesianism *''Cartesian Meditations'', a work by Edmund Husserl *''Cartesian linguistics'', a work by Noam Chomsky *Cartesian theatre, a derisive view of Cartesian dualism coined by Daniel Dennett


*Cartesian diver, a science experiment demonstrating buoyancy and the ideal gas law *Cartesian physics, attempts to explain gravity without a need for action at distance {{disambiguation