cosine
[ kohsahyn ]
/ ˈkoʊ saɪn /

noun
Trigonometry.
 (in a right triangle) the ratio of the side adjacent to a given angle to the hypotenuse.
 the sine of the complement of a given angle or arc. Abbreviation: cos
Mathematics. (of a real or complex number x) the function cos x defined by the infinite series 1 − (x2/2!) + (x4/4!) − + …, where ! denotes factorial. Abbreviation: cosCompare sine(def 3), factorial(def 1).
Nearby words
cosign, cosignatory, cosigner, cosimo, cosimo i, cosine, cosla, cosm, cosmetic, cosmetic surgery, cosmetician
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Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for cosine
British Dictionary definitions for cosine
cosine
/ (ˈkəʊˌsaɪn) /
noun (of an angle)
a trigonometric function that in a rightangled triangle is the ratio of the length of the adjacent side to that of the hypotenuse; the sine of the complementAbbreviation: cos
Word Origin for cosine
C17: from New Latin cosinus; see co, sine 1
Collins English Dictionary  Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for cosine
cosine
1630s, from co. sinus, abbreviation of Medieval Latin complementi sinus (see complement + sine).
Online Etymology Dictionary, © 2010 Douglas Harper
Science definitions for cosine
cosine
[ kō′sīn′ ]
The ratio of the length of the side adjacent to an acute angle of a right triangle to the length of the hypotenuse.
The abscissa 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 cosine of an angle whose measure in radians is equal to x.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.