Manifold

A space that, examined closely enough at any point, looks like ordinary flat Euclidean space — a small enough patch of a sphere’s surface looks like a flat plane, even though the sphere as a whole is curved. Manifolds let geometry and calculus be done locally on shapes too complex to describe with a single flat coordinate system, and the concept extends past the three familiar spatial dimensions to describe the state space of a dynamical system, the parameter space of a synthesis algorithm, or any other space defined by continuously varying quantities.