An opening or drain leading into a plumbing system to provide a location to insert a snake or other implement for cleaning.(noun)
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Use "cleanout" in a sentence
"The contract also stated Egan would rod out the new line and install a cleanout, which is a small access area in the couple's front lawn so they could more easily clear future blockages."
"World Cup 2018: IOC president Jacques Rogge urges Fifa 'cleanout'"
"The arthroscopic procedure performed by Andrews was what's referred to as a "cleanout" of the joint."