Entry 2 senses · 2 variants Webster, 1913 Effluent /ĕf'-lo͞o-ənt/ · Ef·flu·ent · IPA /ˈɛfluənt/ a. n. 01 a. Flowing out; as, effluent beams. 1. Flowing out; as, effluent beams. 02 n. A stream that flows out of another stream or lake. 1. A stream that flows out of another stream or lake.(Geog.)