: a straight line that bisects at right angles a system of parallel chords and divides the curve into two symmetrical portions (as in the parabola which has one such axis, the ellipse which has two, or the circle which has an infinite number)
AXIS OF A CURVE
Meaning of AXIS OF A CURVE in English
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012