[ ˌtrɪgə'nɒmɪtri ]
■ noun the branch of mathematics concerned with the relations of the sides and angles of triangles and with the relevant functions of any angles.
Derivatives
trigonometric -nə'mɛtrɪk adjective
trigonometrical adjective
Origin
C17: from mod. L. trigonometria (see trigon , -metry ).