Alex, thanks for an outstanding thread.
I love abiognostic and ambignostic.
I thrill to pneumacephalic, its regional (?) variant pneumocephalic, and the lovely extended thermopneumacephalic. I think faececephalic (and the rv fececeph.) rocks, though I haven't a clue as to how I'd go about prnouncing it.
For pithy expressiveness, however, Nichola's contribution must take the palm - proctalgic.
Perhaps, though, given that all the roots are from ancient tongues, the word neologism is inappropriate? Palaeologisms or pseudopalaeologisms anyone?
cheer
the sunshine warrior