English word cosine comes from English sine, English co-
| Dictionary entry | Language | Definition |
|---|---|---|
| sine | English (eng) | (trigonometry, mathematics) In a right triangle, the ratio of the length of the side opposite an angle to the length of the hypotenuse. |
| co- | English (eng) | (mathematics) of the opposite, of the counterpart; dual. Partner or subordinate in an activity. To the same degree. Together; mutually; jointly. |
| cosine | English (eng) | (trigonometry) In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse. Symbol: cos. |