Riemann
— Noun
– English
~ pioneer of non-Euclidean geometry (1826-1866)
Riemannian geometry
— Noun
– English
~ (mathematics) a non-Euclidean geometry that regards space as like a sphere and a line as like a great circle; "Bernhard Riemann pioneered elliptic geometry"
riemannian
— Adjective
– English
~ of or relating to Riemann's non-Euclidean geometry