Non-PRO English to Latin Art/Literary Poetry & Literature

As in "ars gratia artis" but replacing "art" with "absurdity". I know that absurd comes from a latin root so this expression should be possible without too much barbarbism, however I cannot remember / figure out which declinaison to use. An approximation will be acceptable.

"absurda gratia absurdis" comes to mind (it rolls off the tongue nicely) but I have no idea whether it is even close to grammatically correct...

/! I would greatly appreciate an explanation of the answer as well (as in, "absurda (or whatever) is the substantive form of XXX root...")