effluent /ˈɛfluːənt/noun 2adjective 1forms 1 noun2 •A stream that flows out, such as from a lake or reservoir; an outflow; effluence.The landscape was dotted with reservoirs and many many effluent streams. •Sewage or waste water discharged into a natural body of water.Residents have little control over the industrial effluent that pollutes their rivers. adjective1 •Flowing out; outflowing. formseffluents