transcription, транскрипция: [ ˈkō-ˌsīn ]
noun
Etymology: New Latin cosinus, from co- + Medieval Latin sinus sine
Date: 1635
1. : a trigonometric function that for an acute angle is the ratio between the leg adjacent to the angle when it is considered part of a right triangle and the hypotenuse
2. : a trigonometric function cos θ that for all real numbers θ is given by the sum of the alternating series cos θ = 1 - θ 2 /2! + θ 4 /4! - θ 6 /6! + θ 8 /8! - . . . and that is exactly equal to the cosine of an angle of measure θ in radians