spherical geometry

Short definition from Wiktionary

Noun

1. 1
   The geometry of the 2-dimensional surface of a sphere;
2. 2
   The geometry of the 2-dimensional surface of a sphere; (countable) a given geometry of the surface of a sphere; a geometry of the surface of a given sphere, regarded as distinct from that of other spheres: a given geometry of the surface of a sphere; a geometry of the surface of a given sphere, regarded as distinct from that of other spheres.