A curve whose ordinate represents the area under another curve; specifically that attributed to Hippias (5th cent. b.c.) in his attempt to trisect an angle, having the formula y = x cotπ x /2 a (in polar coordinates r = 2 a θ/π sin θ).
Mid 17th century. From post-classical Latin quadratrix from classical Latin quadrāt-, past participial stem of quadrāre + -trīx.