\Par`a*cen"tric\, Paracentrical \Par`a*cen"tric*al\,
a. [Pref. para- + centric, -ical: cf. F. paracentrique.]
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 motton} or {velocity}, the motion or velocity of
   a revolving body, 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.