Definition:Sine/Linguistic Note

Linguistic Note on Sine
The sine was originally written about by, under the name ardha-jyā.

The word jyā is a Sanskrit word meaning bow-string, and in the mathematical context means the chord of a circle.

Thus the word ardha-jyā literally means half-chord. Later the first part of the word tended to be omitted, thereby leaving the word jyā.

When the word jyā was translated into Arabic, it was interpreted as jiba. Vowels in Arabic are omitted, leaving the word jb. The word jiba in Arabic is meaningless.

When came to translate these works in the 12th century, he interpreted jb as the word jaib, meaning pocket or fold (in clothing). This he translated into Latin as sinus which has several meanings, of which fold is one, and curve, winding or bay are others.

The word sine is pronounced the same way as the English word sign.