Cleanout
A capped pipe fitting that gives access to clear a drain or sewer line.
A cleanout is a capped Y- or T-shaped fitting in a drain or sewer line that lets a plumber insert a snake or auger to clear blockages. They're often found near where the main drain leaves the house, in basements, or in the yard. Knowing where yours is saves time during a backup; never permanently bury or pave over one.