The term "trigonometry" was derived from the Greek word "τριγωνομετρία" ("trigonometria"), meaning "triangle measuring", from "τρίγωνο" (triangle) plus "μετρεῖν" (to measure).

Our modern word "sine" is derived from the Latin word sinus, which means "bay", "bosom" or "fold", translating Arabic jayb. The Arabic term is in origin a corruption of Sanskritjīvā, or "chord". Sanskrit jīvā in learned usage was a synonym of jyā "chord", originally the term for "bow-string". Sanskrit jīvā was loaned into Arabic as jiba.[1][2] [clarification needed]This term was then transformed[2] into the genuine Arabic word jayb, meaning "bosom, fold, bay", either by the Arabs or by a mistake[1] of the European translators such asRobert of Chester (perhaps because the words were written without vowels[1]), who translated jayb into Latin as sinus.[3] Particularly Fibonacci's sinus rectus arcus proved influential in establishing the term sinus.[4] The words "minute" and "second" are derived from the Latin phrases partes minutae primae and partes minutae secundae.[5] These roughly translate to "first small parts" and "second small parts".