paracentric

par`a`cen´tric

(păr`å`sĕn´trĭk)

Deviating from circularity; changing the distance from a center.

Paracentric curve
(Math.) a curve having the property that, when its plane is placed vertically, a body descending along it, by the force of gravity, will approach to, or recede from, a fixed point or center, by equal distances in equal times; - called also a paracentric.

Paracentric motion
the motion or velocity of a revolving body, such as a planet, by which it approaches to, or recedes from, the center, without reference to its motion in space, or to its motion as reckoned in any other direction.