1. an underground watercourse, a conduit, main MN.i.171; AN.ii.189; Ja.vi.426, Ja.vi.432; Snp-a.50 (“ummaggo paññā pavuccati”) Dhp-a.i.252 (˚cora); Dhp-a.ii.37 (v l. umanga); Dhp-a.iv.104; Pv-a.44 (read with variant reading SS kummagga).
2. a side track, a wrong way, devious way SN.i.193 (variant reading ˚manga) = Thag.1242; SN.iv.195; AN.iv.191.

ud + magga, lit. “off-track”