1 the trigonometric function that is equal to the ratio of the side opposite a given angle (in a right-angled triangle) to the hypotenuse.
2 a function of the line drawn from one end of an arc perpendicularly to the radius through the other.
Phrases and idioms:
sine curve (or wave) a curve representing periodic oscillations of constant amplitude as given by a sine function: also called SINUSOID.
Etymology: L sinus curve, fold of a toga, used in med.L as transl. of Arab. jayb bosom, sine
Useful english dictionary. 2012.