sine

American  

[sahyn] / saɪn /

noun

• sines
  plural

1. Trigonometry.

   1. (in a right triangle) the ratio of the side opposite a given acute angle to the hypotenuse.

   2. (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. sin

2. Geometry. (originally) a perpendicular line drawn from one extremity of an arc of a circle to the diameter that passes through its other extremity.

3. Mathematics. (of a real or complex numberx ) the function sin x defined by the infinite series x − (x 3 /3!) + (x 5 /5!) − + …, where ! denotes factorial.

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sine ¹ British  

/ ˈsaɪnɪ /

preposition

1. (esp in Latin phrases or legal terms) lacking; without

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sine ² British  

/ saɪn /

noun

1.  sin. 

   1. a trigonometric function that in a right-angled triangle is the ratio of the length of the opposite side to that of the hypotenuse

   2. a function that in a circle centred at the origin of a Cartesian coordinate system is the ratio of the ordinate of a point on the circumference to the radius of the circle

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sine Scientific  

/ sīn /

1. The ratio of the length of the side opposite an acute angle in a right triangle to the length of the hypotenuse.

2. 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.

3. A function of a number x, equal to the sine of an angle whose measure in radians is equal to x.

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Other Word Forms

Noun Inflected Forms

• sines
  plural

Etymology

Origin of sine

1585–95; < New Latin, Latin sinus a curve, fold, pocket, translation of Arabic jayb literally, pocket, by folk etymology < Sanskrit jiyā, jyā chord of an arc, literally, bowstring

Example Sentences

See Examples For:

sine sines

There have been about 400 cases of legal action against home care customers in the North-West sine 2022.

From BBC ● Apr. 23, 2026

In Division 5, Rio Hondo Prep is 13-0 and going for a third consecutive title against Redondo Union, which is making its first championship appearance sine 1944.

From Los Angeles Times ● Nov. 23, 2025

“But now speed and maneuverability are the sine qua non.”

From The Wall Street Journal ● Oct. 28, 2025

He talks a lot about what you just mentioned, which is the sort of sine curve of public interest in surveillance.

From Salon ● Aug. 21, 2024

By the winter of that year, the sine curve of Rajesh’s psyche had tightened in its frequency and gained in its amplitude.

From "The Gene" by Siddhartha Mukherjee

Then, we divide by 2 to isolate the product of sines:

From Textbooks ● Feb. 13, 2015

The identities can be verified using other formulas or by converting the expressions to sines and cosines.

From Textbooks ● Feb. 13, 2015

Likewise, the coversine is the versine of the complementary angle, as you can see in light blue above one of the red sines in the diagram at the top of the post.

From Scientific American ● Sep. 16, 2013

And the next thing I knew I was in a trigonometry class and they’re talking about sines and cosines without any mention that it had something to do with triangles.

From Scientific American ● Dec. 1, 2011

Werner takes it without looking and begins to calculate the sines.

From "All the Light We Cannot See" by Anthony Doerr