A non-Euclidean space with constant negative Gaussian curvature.
Gauss-Bolyai-Lobachevsky Space
See also
Hyperbolic Geometry, Non-Euclidean GeometryExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Gauss-Bolyai-Lobachevsky Space." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Gauss-Bolyai-LobachevskySpace.html