PARACENTRIC
Par`a*cen"tric, Par`a*cen"tric*al, a. Etym: [Pref. para- + centric, -
ical: cf. F. paracentrique.]
Definition: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition