hyperbolic

The hyperbolic surface, which has so-called negative curvature because its surface curves up and down at the same time, like a saddle, just might represent the shape of the universe..双曲表面，即通常所称的负曲率，因为它的表面曲线同时有的向上和有的向下，像一个马鞍，也许这样就可以代表宇宙的形状。

hyperbolic equation,双曲型方程

hyperbolic function,双曲线函数

hyperbolic tangent,双曲正切

hyperbolic curve,双曲线

hyperbolic secant,双曲正割