Plug
1. An object used to stop up a hole or gap. 
2. Wood or other filler used in filling a hole. 
3. An electrical device (male fitting) with projecting prongs, to be fitted into an outlet to make contact and provide electrical power. 
4. A small wedge or segment cut from something. 
5. Threaded fitting to screw in to the end of a female pipe-fitting to seal it closed. 

Plug and Feather Rock Splitter 
Device used to split rock which is a split plug with an internal taper along with a feather, a wedge shaped rod. When the plug is drilled into the rock, the feather is wedged into the plug, forcing it apart and splitting the rock. 

Plug Gauge
Inside diameter gauge used to measure, with precision, small holes for dowels, tap sizes, etc. and for precision work on machines. 

Plug-in Bus Duct 
Electrical conductor, which is mounted in a sheet metal enclosure, called a bus, which goes through an industrial building to provide power, with the use of plug in ports along the length of the bus, to lathes and other heavy equipment. 

Plug-in Strip 
Electrical wiring strip, encased in a cover, which has outlets for plugs. 

Plug Weld 
Weld which is made through a hole in a piece of metal to fasten the piece to another piece below the hole or for filling in the hole. 

Plumb 
An absolutely straight vertical. 

Plumb Bob or Plummet
A lead weight, often pointed at the bottom end, hung at the end of a line and left freely swinging, to determine whether something is perfectly vertical. Since gravity forces the cord to hang in an absolute vertical, the plumb bob is used to align walls and any surface that must be completely straight. 

Plumb Cut 
An absolutely straight up and down vertical cut at the top end of a rafter where it touches the ridge. 

Plumb Line 
String line that holds the lead weight and which hangs freely and swings to allow gravity to force the cord to hang in an absolute vertical. 

Plumb Rule 
Bubble indicator, in the middle of a board, which centers between two vertical lines when the board is plumb. 

Plumber 
Tradesman who installs and repairs plumbing systems. 

Plumber's Friend or Helper
The device normally used to unclog toilets, consisting of a long handle with a rubber cup on the end. When the cup is fitted over the drain and pushed toward the drain by pressure exerted on the handle, the air in the cup is compressed and force is exerted on the obstruction in the drain and pushes it through to clear the pipe. This is also referred to as a force cup. 

Plumber's Strap or Tape
Galvanized steel strap with holes along the length, which helps support smaller pipes.

Plumbing 
Collective term for the pipes and fixtures, etc. involved with the movement of fluid throughout a building. 

Plumbing Bend 
Elbow fitting, used in drain and vent lines, to make a bend at an angle to the main line. 

Plumbing Bend, Closet 
Elbow fitting, connecting to the outlet of a toilet.

Plumbing Bend, Long Sweep
Elbow with a long radius. 

Plumbing Bend, Reducing Sweep 
Elbow fitting, with one end larger than the other for the ability to change direction or adjust a pipe size change. 

Plumbing Bend, Return 
Elbow fitting with a 180-degree bend. 

Plumbing Bend, Standard Bend
Elbow with a short radius.

Plumbing Double Y-Branch 
Also called a double wye fixture, this fitting has branches coming in at an angle on each side of the main to join the main run.

Plumbing Drawing Symbols 
Symbols used to denote specific fittings, etc. of drawing. 

Plumbing Fixture 
Mechanism which both receives and discharges wastes and water into a drainage system. 

Plumbing, Rough In 
Plumbing system installation which prepares for but does not include the installation of fixtures. 

Plumbing Sanitary Tee 
Type of tee used in sanitary waste lines because its short-patterned 90 degree configuration allows the right angle portion of the tee to curve into the run section in the same direction of the flow causing no abrupt change of direction. 

Plumbing Snake 
Thin, flexible length of spiral-wound metal, which is inserted into a drain and rotated to clear anything that is clogged in the pipes. 

Plumbing Y-Branch
Y-shaped fitting, also called a wye, which has one straight side and a branch joining at an angle and is used to join a branch line and a main run. 

Ply
A single thickness, fold or layer of a multi-layered substance. 

Plyclips
Also called metal edge support clips and plywood edge clips, these metal clips reach between adjacent edges of plywood panels to connect them. 

Plyform
Trade name of a plywood that is made from woods chosen for durability that are bonded with exterior grade waterproof glue and sanded and oiled to minimize moisture penetration. Since it is used for concrete forms, moisture penetration reduction and a lessened potential to stick to the concrete as it cures is vital. 

Plyform, HDO 
Trade name of a high density overlaid Plyform, which has improved longevity due to the material (resin) that is bonded to the Plyform. More expensive than regular Plyform, it is used on a longer term concrete job where it is necessary for forms to last longer. 

Plytooth Saw Blade 
Saw blade, used for cutting plywood, due to the fact that this finer tooth blade splinters the wood less. 

Plywood
Wood make of three or more layers of veneer joined with glue, usually laid with the grain of adjoining plies at right angles to one another. This arrangement makes plywood strong and highly resistant to movement from expansion and contraction. This lack of cracking keeps paint and finishing problems to a minimum. Plywood has innumerable uses, from roof decking to siding and cabinets. 

Plywood Edge Clips 
Also called metal edge support clips and plyclips, these metal clips reach between adjacent edges of plywood panels to connect them. 

Plywood, Exterior 
Plywood, made with waterproof glue, that is used for exterior applications. 

Plywood Grades 
Ratings of the quality of plywood which include Grade 1, which is the best available and can be even used for furniture, to Grade 4 which is sound but defective in appearance. 

Plywood, Interior 
Plywood which is not suited for exterior use because the glue can only be resistant to moderate moisture. 

Plywood, Lumber Core 
Plywood which has a core of boards, enclosed in both a top and bottom layer consisting of 1/16 inch thick board covered by two 1/28 inch facing layers.

Plywood, Veneer 
Plywood with several glued together layers of veneer with a higher quality wood outer layer.

PMI (private mortgage insurance) 
Insurance on some loans, which protects lenders from possible default by borrower. Conventional loans with down payments of less than 20 per cent of the home value usually require private mortgage insurance (PMI).

Pneumatic 
Powering by use of compressed air. 

Pneumatic Roller 
Paving machine that compacts surfaces, by rolling them, without having the soil adhere to the wide, smooth, air filled tires.