affluent:  The meaning ‘rich’ is a fairly recent development for affluent; it is first recorded in the mid 18th century. Originally the adjective meant simply ‘flowing’. It came, via Old French, from Latin affluent-, the present participle of affluere, a compound verb formed from the prefix ad- ‘towards’ and fluere ‘flow’ (the source of English fluid, fluent, flux, fluctuate, and many other derivatives). => fluctuate, fluent, fluid, flux
mid-15c., "flowing," from Middle French affluent (14c.) or directly from Latin affluentem (nominative affluens) "flowing toward, abounding, rich, copious," present participle of affluere "flow toward," from ad- "to" (see ad-) + fluere "to flow" (see fluent).
1. The Strand is one of London's busiest and most affluent streets.
2. The diet of the affluent has not changed much over the decades.
3. a very affluent neighbourhood
4. He is an affluent man.
5. It's a fallacy that the affluent give relatively more to charity than the less prosperous.