The term "trigonometry" was derived from Greek τρίγωνον trigōnon, "triangle" and μέτρον metron, "measure" [REF].
This term was then transformed[REF] into the genuine Arabic word jayb, meaning "bosom, fold, bay", either by the Arabs or by a mistake[REF] of the European translators such as Robert of Chester (perhaps because the words were written without vowels[REF]), who translated jayb into Latin as sinus [REF].