The term "trigonometry" is a modern Latin construction from the early 17th century, directly assembled from Greek components. It literally means "the measurement of triangles," combining trigōnon (a three-cornered or three-angled figure) and -metria (the art or science of measuring). While the Greek gōnia (angle) is the source for the "gon" in polygon and pentagon, its specific combination with "tri-" was fossilized into the Neo-Latin form "trigono-" for this mathematical context. Thus, the word's logic perfectly encapsulates its function: it is the mathematical system for calculating the measurements—of sides, angles, and ratios—within and derived from triangular forms.

Structure: trigono (triangle) + metry (measurement) - trigono: From Greek trigōnon (triangle), from tri- (three) + gōnia (angle, corner). Functions as the core semantic root specifying the object of study. - metry: From Greek -metria (measurement), from metron (measure). Functions as a combining form indicating the science or process of measuring.