sine

American  

[sahyn] / saɪn /

noun

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.

---

sine ¹ British  

/ ˈsaɪnɪ /

preposition

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

---

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

---

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.

---

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

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

From BBC • Apr. 23, 2026

“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

The Mary Chain’s albums “Psychocandy,” “Darklands” and “Automatic” became the sine qua non of the 1980s alternative rock movement and carried the band well into the ’90s.

From Los Angeles Times • May 10, 2024

Dr Strauss says that so far Algernon looks like he mite be smart permanint and he says thats a good sine becaus we both had the same kind of operashun.

From "Flowers for Algernon" by Daniel Keyes