Origin: 1400–50; late Middle English < Middle French < Latin affluent- (stem of affluēns rich; orig. present participle of affluere), equivalent to af-af- + flu- flow + -ent-ent
mid-15c., "flowing," from L. affluentem (nom. affluens), prp. of affluere "flow toward," from ad- "to" + fluere "to flow" (see fluent). Notion of "a plentiful flow" (of the gifts of fortune) led to affluence in the sense of "wealth," first recorded c.1600.