Riemannian geometry

noun2

1. •
   The branch of differential geometry that concerns Riemannian manifolds; an example of a geometry that involves Riemannian manifolds.

   • Riemannian geometry was introduced by Riemann in 1854 as the n-dimensional generalization of the theory of curved surfaces of the 3D Euclidean space. — 2001
2. •
   The geometry of elliptical and spherical shapes.