Green’s Dictionary of Slang

(US campus) excessively obscure, complex.

1988		Design Book Rev. 14-15 49: He has a record that nobody need be ashamed of, starting in the mid- fifties, and deflecting gently to accommodate the changes that have given us Brutalism, PoMo, and High Tech along the way.
1996		M. Cross Advertising & Culture 79: If PoMo is the sardonic mixing of high and low styles, then it must be a sort of game.
2014		C. Eble (ed.) UNC-CH Campus Sl. Spring 2014 Fall 5: POMO — < post modern convoluted, illogical: ‘That professor always writes pomo tests where all the answer choices seem right’.
2016		Guardian 2 May 16/1: Built in 1995 by Swiss po-mo maestro Mario Botta it looks more like a giant meringue.