Cosine

• POS: Noun
• HYPHEN: co=sine

CIDE DICTIONARY

Cosine, n. [For co. sinus, an abbrev. of L. complementi sinus.].

 The sine of the complement of an arc or angle. See Illust. of Functions.  [1913 Webster]

OXFORD DICTIONARY

Cosine, n. Math. the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse.

Etymology

mod.L cosinus (as CO-, SINE)