sine

The word "sine" has a fascinating history of mistransmission. It originates from the Latin word "sinus," which meant "curve," "fold," or "bay." This Latin term was used in medieval Arabic translations of Sanskrit mathematical texts. The Sanskrit word "jya" (chord) was often abbreviated as "jiva." Arabic scholars transcribed this as "jiba," but in written Arabic without short vowels, this was confused with "jaib," meaning "bosom" or "fold," which was then translated into Latin as "sinus." The modern trigonometric function, representing a ratio of lengths in a right triangle, thus derives its name from this Latin word for a curve or fold, reflecting the geometric concept of a chord in a circle. The current form "sine" is a later phonetic simplification from the Latin genitive form "sinus."

The word "sine" is a simplex loanword from Latin. It does not contain separable morphemes in its modern English spelling.