a branch of non-Euclidean geometry in which a line may have many parallels through a given point. It has a model on the surface of a sphere, with lines represented by great circles
Also called: elliptic geometry
Riemannian geometry in American English
(riˈmɑniən)
a form of non-Euclidean geometry in which there are no parallel lines, since itsfigures can be conceived as constructed on a curved surface where all straight lines intersect, and in which the sum of the angles of a triangle exceeds 180°
Word origin
after G. F. B. Riemann (1826-66), Ger mathematician