hyperbolic function  
—n  
any of a group of functions of an angle expressed as a relationship between the distances of a point on a hyperbola to the origin and to the coordinate axes. The group includes sinh (hyperbolic sine), cosh (hyperbolic cosine), tanh (hyperbolic tangent), sech (hyperbolic secant), cosech (hyperbolic cosecant), and coth (hyperbolic cotangent) 
hyperbolic function (hī'pərbŏl'ĭk) Pronunciation Key
Any of a set of six functions related, for a real or complex variable x, to the hyperbola in a manner analogous to the relationship of the trigonometric functions to a circle, including: a. The hyperbolic sine, defined by the equation sinh x = ^{1}/_{2} (e^{x}  e^{x}).
