trigonometry
Concise Oxford English Dictionary © 2008 Oxford University Press:
trigonometry /ˌtrɪgəˈnɒmɪtri/
▶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 /-nəˈmɛtrɪk/ adjective,
trigonometrical adjective.
trigonometric /-nəˈmɛtrɪk/ adjective,
trigonometrical adjective.
'trigonometry' also found in these Oxford entries:

