versine
/ˈvɜːrsaɪn/Definitions
1. noun
A trigonometric function, equal to 1 - cosine, used in navigation and geometry.
“The ancient mariner used a versine to calculate the angle of the rising sun.”
2. noun
A component of a quadrature, especially one that is a trigonometric function.
“The versine of this quadrature is used to calculate the area of a circle.”