Cartesian means of or relating to the French philosopher and mathematician René Descartes—from his name—Rene Des-Cartes. It may refer to:
- Cartesian anxiety
- Cartesian circle
- Cartesian dualism, the philosophy of the distinction between mind and body developed by René Descartes
- Cartesianism, name given to 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
- Cartesian diver, a science experiment
- Cartesian physics
In mathematics:
- 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