Origin: Latin suffix -tion
Trigonometric function has 2 different meanings across 1 category:
function of an angle expressed as a ratio of the length of the sides of right-angled triangle containing the angle
Any function of an angle expressed as the ratio of two of the sides of a right triangle that has that angle, or various other functions that subtract 1 from this value or subtract this value from 1 (such as the versed sine)