Definition:Trigonometric Function

Definition
There are six basic trigonometric functions: sine, cosine, tangent, cotangent, secant, and cosecant.

Also known as
A trigonometric function is sometimes referred to as a direct trigonometric function so as to distinguish it from an inverse trigonometric function.

Some sources use the terms cyclometric function or circular function.

Some older sources refer to a trigonometric function as a trigonometric ratio.