Noun
hyperbolic cosine (plural hyperbolic cosines)
(mathematics) a hyperbolic function that is written in symbol cosh and defined as the following:
cosh
(
x
)
=
1
2
(
e
x
+
e
−
x
)
{\displaystyle \cosh(x)={\tfrac {1}{2}}(e^{x}+e^{-x})}