The Collaborative International Dictionary of English v.0.48:

Outflow \Out*flow"\, v. i.
   To flow out. --Campbell.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Outflow \Out"flow`\, n.
   A flowing out; efflux.
   [1913 Webster]

WordNet (r) 3.0 (2006):

outflow
    n 1: the discharge of a fluid from some container; "they tried
         to stop the escape of gas from the damaged pipe"; "he had
         to clean up the leak" [syn: escape, leak, leakage,
         outflow]
    2: the process of flowing out [syn: outflow, effluence,
       efflux] [ant: inflow, influx]
    3: a natural flow of ground water [syn: spring, fountain,
       outflow, outpouring, natural spring]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "outflow":
   affluence, afflux, affluxion, blow out, concourse, confluence,
   conflux, course, crosscurrent, current, defluxion, discharge,
   downflow, downpour, drain, drain out, drainage, drift, driftage,
   effluence, efflux, effluxion, effusion, empty, exhalation, exhaust,
   find vent, flow, flow out, flowing, flowoff, fluency, flux, gush,
   gush out, inflow, jet, mill run, millrace, money going out, onrush,
   onward course, outfall, outflowing, outgo, outgoings, outlay,
   outpour, outpouring, pour, pour out, race, run, run out, runoff,
   rush, set, sluice out, spate, spendings, spew out, spout,
   spout out, spurt, stream, surge, tide, trend, undercurrent,
   undertow, vomit forth, water flow, well, well out