(in a right triangle) the ratio of the side opposite a given acute angle to the hypotenuse.
(of an angle) a trigonometric function equal to the ratio of the ordinate of the end point of the arc to the radius vector of this end point, the origin being at the center of the circle on which the arc lies and the initial point of the arc being on the x-axis.
Geometry. (originally) a perpendicular line drawn from one extremity of an arc of a circle to the diameter that passes through its other extremity.
Mathematics. (of a real or complex number x) the function sin x defined by the infinite series x − (x3 /3!) + (x5 /5!) − + …, where ! denotes factorial.
trigonometric function, 1593 (in Thomas Fale's "Horologiographia, the Art of Dialling"), from L. sinus "fold in a garment, bend, curve." Used by Gherardo of Cremona c.1150 in M.L. translation of Arabic geometrical text to render Arabic jiba "chord of an arc, sine" (from Skt. jya "bowstring"), which he confused with jaib "bundle, bosom, fold in a garment."
The ratio of the length of the side opposite an acute angle in a right triangle to the length of the hypotenuse.
The ordinate of the endpoint of an arc of a unit circle centered at the origin of a Cartesian coordinate system, the arc being of length x and measured counterclockwise from the point (1, 0) if x is positive or clockwise if x is negative.
A function of a number x, equal to the sine of an angle whose measure in radians is equal to x.