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[sahyn] /saɪn/
  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.
    Abbreviation: sin.
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 − (x 3 /3!) + (x 5 /5!) − + …, where ! denotes factorial.
Compare cosine (def 2), factorial (def 1).
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

nil sine numine

[neel sin-e noo-mi-ne; English nil sin-ee noo-mi-nee, nyoo-] /nil ˈsɪn ɛ ˈnu mɪ nɛ; English nɪl ˈsɪn i ˈnu mɪ ni, ˈnyu-/
nothing without the divine will: motto of Colorado.

causa sine qua non

[kou-sah si-ne kwah nohn; English kaw-zuh sahy-nee kwey non, kaw-zuh sin-ey kwah nohn] /ˈkaʊ sɑ ˈsɪ nɛ kwɑ ˈnoʊn; English ˈkɔ zə ˈsaɪ ni kweɪ ˈnɒn, ˈkɔ zə ˈsɪn eɪ kwɑ ˈnoʊn/
noun, Latin.
an indispensable condition; requisite.
literally, a cause without which not Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for sine


noun (of an angle)
  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
Word Origin
C16: from Latin sinus a bend; in New Latin, sinus was mistaken as a translation of Arabic jiba sine (from Sanskrit jīva, literally: bowstring) because of confusion with Arabic jaib curve


(esp in Latin phrases or legal terms) lacking; without
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for sine

trigonometric function, 1590s (in Thomas Fale's "Horologiographia, the Art of Dialling"), from Latin sinus "fold in a garment, bend, curve, bosom" (see sinus). Used mid-12c. by Gherardo of Cremona in Medieval Latin translation of Arabic geometrical text to render Arabic jiba "chord of an arc, sine" (from Sanskrit jya "bowstring"), which he confused with jaib "bundle, bosom, fold in a garment."

Online Etymology Dictionary, © 2010 Douglas Harper
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sine in Science
  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.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Related Abbreviations for sine


sign, that is, operator's personal initials (shortwave transmission)
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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