General English


  • noun liquid, semisolid or gas waste from industrial processes or material such as slurry or silage effluent from a farm


  • In sanitary engineering, the liquid sewage discharged as waste, as in the discharge from a septic tank.
  • Generally, the discharged gas, liquid, or dust by-product of a process.

Origin & History of “effluent”

Effluent is that which ‘flows out’. The word comes from the present participle of Latin effluere, a compound verb formed from the prefix ex- ‘out’ and fluere ‘flow’ (source of English fluctuate, fluent, fluid, flux, and a host of derivatives). English originally acquired it as an adjective in the 18th century, but did not begin to use it in its present-day noun senses until the mid 19th century. From the same source come effluvium (17th c.) and efflux (17th c.).