Plumb in Definition 1 of 2Pro Tip 1/3Plumbing Context Used when talking about connecting water or waste systems, often in a domestic setting. We'll need to plumb in the dishwasher next. Pro Tip 2/3Physical Activity The action usually involves manual work, often done by a professional plumber. Can you plumb in the sink while I tile the floor? Pro Tip 3/3Technical Aspect Emphasizes the technical know-how needed to correctly connect plumbing fixtures. You'll need to plumb in the valve accurately, or it might leak.