Learner's definition of PLUMBING
1 : a system of pipes that carries water through a building
The house has old plumbing.
The cottage has electricity but no indoor plumbing. [=the cottage does not have a toilet or sink; there are no pipes that supply clean water to the cottage]
a store that sells plumbing fixtures [=sinks, toilets, faucets, etc.]
2 : the work of a plumber : the job of installing and repairing sinks, toilets, water pipes, etc.