| ABS | – | Acrylonitrile-Butadiene-Styrene; a rigid plastic drainpipe |
| Adapter | – | Connects one type of pipe to another |
| Cap | – | Fitting with a solid end used for closing off a pipe |
| Center-to-center | – | In mounting faucets: the distance between centers of holes on a sink deck. In pipefitting:Distance between centers of two consectutive pipes. |
| Cleanout | – | Opening providing access to a drainline or trap; closed with a threaded cleanout plug. |
| Compression Fitting | – | Easy-to-use fitting for copper or plastic tube. Pushed in and hand-tightened |
| Compression Nut | – | Used with a compression ring to join a flexible tube to a compression fitting. |
| Coupling | – | Fitting used to connect two lengths of pipe in a straight run. |
| Coupling Nut | – | Holds a supply tube to a faucet inlet or a toilet inlet valve. |
| CPVC | – | Chlorinated polyvinyl chloride; rigid plastic tube for hot and cold water. |
| Critical distance | – | Maximum horizontal distance allowed between a fixture trap and a vent or soil stack. |
| Cross connection | – | Plumbing connection that could mix contaminated water with potable water supply. |
| DWV | – | Drain-waste and vent; system that carries away waste water and solid waste, allows sewer gases to escape, and maintains atmospheric pressure in drain pipes. |
| Elbow | – | Fitting used for making turns in pipe runs (i.e. and 90° elbox makes a right-angle turn) |
| Escutcheon | – | Decorative trim piece that fits over a faucet body of pipe extending from a wall. |
| Female | – | Pipes, valves, or fittings with internal threads. |
| Fitting | – | A device used to join pipes. |
| Fixture | – | A non-powered water-using devide such a sink, bathtub, shower, or toilet. |
| Flange | – | Flat fitting or integral edging with holes to permit bolting together (a toilet bowl is bolted to a floor flange) or fastening to another surface (a tub is fastened to a wall through an integral flange). |
| Flare Fitting | – | Threaded fitting used on copper and plastic pipe that requires enlarging one end of the pipe |
| Flexible Connector | – | Bendable piece of tubing that delivers water from a shutoff valve to a fixture or appliance. |
| Flue | – | Large pipe through which fumes escape from a gas water heater. |
| Gasket | – | Device (usually rubber) used to make a joint between two parts watertight. Sometimes used interchangeably with washer. |
| Hose Bibb | – | Valve with an external threaded outlet for accepting a hose fitting. |
| Joist | – | A horizontal wood framing member placed on edge, as a floor or ceiling joist. |
| Locknut | – | Nut used to secure a part, such as a toilet water inlet valve, in place |
| Male | – | Pipes, valves, or fittings with external threads. |
| Nipple | – | Short piece of pipe with male threads used to join two fittings. |
| No-hub | – | Cast-iron pipe joined with neoprene gaskets and clamps |
| O-ring | – | Narrow rubber ring; used in some faucets as packing to prevent leaking around stem and in swivel-spout faucets to prevent leaking at base of spout. |
| Packing | – | Material that stops leaking around the stem of a faucet or valve. |
| PB | – | Polybutylene; flexible plastic tubing for hot or cold water. |
| PE | – | Polyethylene; flexible plastic tubing for cold water outdoors. |
| Pipe | – | Drain pipe or supply pipe that is sized nominally by iron pipe sizes. |
| Pipe-joint compound | – | Sealing compond used on threaded fittings (applied to external threads). |
| Pipe-thread tape | – | Special tape used as a joint sealer in place of pipe-joint compound. |
| Plug | – | Externally-threaded fitting for closing off a fitting that has internal threads. |
| PP | – | Polypropylene; rigid plastic pipe used for traps |
| Pressure regulator | – | Device installed in a water supply line to reduce water pressure. |
| PVC | – | Polyvinyl Chloride; rigid plastic pipe for cold water outdoors or off-white piping used for DWV systems. |
| Reducer | – | Fitting that connects pipe of one diameter with pipe of a smaller diameter |
| Riser | – | Vertical run of pipes. |
| Saddle tee | – | T-fitting that is fastened onto side of pipe, eliminating cutting and threading or soldering; usually requires drilling into pipe. |
| Sanitary fitting | – | Fitting with smooth bends and no inside shoulders to block flow of waste; used to join DWV pipe. |
| Silicone grease | – | A type of synthetic grease used to lubricate faucet parts; non-petroleum base, won’t break down rubber parts. |
| Siphoning | – | Action occuring when atmospheric pressure forces water into a vacuum in a pipe. |
| Slip Coupling | – | Used to join a new fitting into a run of copper or plastic tubing. It is unthreaded and has no center shoulder,so it can slide along a tube. |
| Slip Nut | – | Used on a drain (such as a sink trap). Threads onto one pipe and compresses a washer around the other to form a slip joint. |
| Soil stack | – | Large DWV pipe that connects toilet and other drains to house drain and also extends up and out house roof (the upper portion serving as a vent). |
| Solvent Cement | – | Compound used to join rigid plastic pipes and fittings. |
| Spacer | – | Short piece of unthreaded plastic or copper pipe cut to size; used when reparing or extending pipe. Sometimes referred to as a nipple. |
| Stubout | – | End of a supply pipe or drainpipe that extends from a wall or floor |
| Stud | – | A vertical wood framing member; also known as a wall stud. Attached to a sole plate below and a top plate above. |
| Sweat soldering | – | A method of using heat to join copper tube and fittings. |
| T-fitting | – | Also known as a tee, it is a T-shaped fitting with 3 openings. |
| Transition fitting | – | Adapter fitting that joins pipes of plastic and metal. |
| Trap | – | Device (usually a curved section of pipe) that holds a water seal to prevent sewer gases from escaping into a home through a fixture drain. |
| Tube | – | Supply pipe that is sized nominally by copper water tube sizes. |
| Union | – | Fitting that joins two lengths of pipe permitting assembly and disassembly without taking the entire section apart. |
| Valve | – | Device that controls that flow of water. |
| Washer | – | A flat thing ring of metal or rubber used to ensure a tight fit and prevent friction in joints and assemblies. Sometimes used interchangeably with gasket. |
| Y-Fitting | – | Or wye; DWV fitting with 2 outlets in shape of the letter Y. |
