epicycle

plural epicycles

1. astronomyA small circle whose centre is on the circumference of a larger circle; in Ptolemaic astronomy it was seen as the basis of revolution of the "seven planets", given a fixed central Earth.

   Is it not [Philosophie], that […] teacheth miserie, famine and sicknesse to laugh? Not by reason of some imaginarie Epicicles, but by naturall and palpable reasons.

   , Folio Society, 2006, vol.1, p.155

2. geometryAny circle whose circumference rolls around that of another circle, thus creating a hypocycloid or epicycloid.
3. chemistryA ring of atoms joining parts of an already cyclic compound
4. figurativelyAn ad hoc complication added to a model to make it fit the known data

   If two chronicles seemed contradictory, instead of trying to choose between them, a rationalization (epicycle) was devised to cover both.

   1978, The Journal of the Siam Society, volumes 66-67, page 152

   1 more example

   Rather than solve the theoretical problem of how to produce a method of political ethics, the contractarian device introduces an unnecessary theoretical epicycle into what is otherwise a coherent account of social justice in particular and political morality in general.

   1998, Paul Joseph Kelly, Impartiality, Neutrality and Justice: Re-reading Brian Barry’s Justice as Impartiality, page 12