Meaning

noun an affluent person; a person who is financially well off

noun a branch that flows into the main stream

adjective having an abundant supply of money or possessions of value

originBorrowed from Middle French affluent, borrowed in turn from Latin affluentem, accusative singular of affluēns, present active participle of affluō (“flow to or towards; overflow with”), from ad (“to, towards”) + fluō (“flow”) (cognate via latter to fluid, flow). Sense of “wealthy” (plentiful flow of goods) c. 1600, which also led to nominalization affluence. By surface analysis, af- + fluent.

Etymology from Wiktionary, CC BY-SA 3.0