[cat.a.comb] n [MF catacombe, prob. fr. OIt catacomba, fr. LL catacumbae, pl.] (15c) 1: a subterranean cemetery of galleries with recesses for tombs--usu. used in pl.
2: something resembling a catacomb: as a: an underground passageway or group of passageways b: a complex set of interrelated things "the endless ~s of formal education --Kingman Brewster, Jr."