# Definition of 'cosine'

noun (of an angle)

a trigonometric function that in a right-angled triangle is the ratio of the length of the adjacent side to that of the hypotenuse; the sine of the complement

. Abbreviation: cosCollins English Dictionary. Copyright © HarperCollins Publishers

## Word origin of 'cosine'

C17: from New Latin cosinus; see co-, sine1 noun Trigonometry
Mathematics

the reciprocal of the secant

; specif.
b.

an equivalent, positive or negative ratio for certain related angles (Ex.: the cosine of 57° or 303° is .5446, of 123° or 237° is -.5446) or real numbers representing radians (Ex.: cosine of .9948 radians (57°) is .5446)

Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.

## Word origin of 'cosine'

ModL < co. sinus, short for complementi sinus, lit., sine of the complement## Word Lists

Mathematical terms## Trends of 'cosine'

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