The following Glossary of Locksmith Terminology is provided courtesy of the Master Locksmith Association (MLA). Click on a letter below to be taken to its corresponding terms.

Padlock - A comparatively small removable and portable locking device, usually but not always key operated on one side only. The locking member is a circular hinged sliding or swivelled shackle which passes through a hole in a staple, locking bar or similar member.

Pan - The removable mechanism chamber attached to the inside face of a safe door.

Panel grilles - Steel grilles made to size with various infills of expanded diamond mesh, square weldmesh or fancy infills, usually fitted internally.

Passing (or to pass) - Any key which operates a lock is said to pass the lock. If locks are made “alike change” one key will pass all the locks.

Peg Ward - A combination of wards resembling a sash ward but fixed by pegs to the lock case.

Pin key - A key with solid shank (usually but not always circular) and a projecting blade at one end and a bow at the other.

Pin tumbler mechanism - The mechanism incorporated in the cylinder or body of a cylinder pin tumbler lock, latch or padlock, usually referred to as a cylinder lock, latch or padlock. Other than padlocks, the cylinder with its co-axial plug housing the pins and drivers under spring pressure passes through the thickness of the door, and the correct key lines up the pins and drivers to make a clear line of intersection between plug and cylinder, thus allowing the plug to rotate and the lock to be operated. The mechanism offers high security against key interchangeability and anti-pick mushroom drivers are usually included in every cylinder. For example, Yale 5 pin cylinders offer up to 24,000 differs as standard. It is also very suitable for master keying, as many different types of locks or latches can be included in the suite. Under master key, 12,200 differs are obtainable and under grand master key, 36 different sub suites with up to a total of 2,200 differs can be provided.

Pins - Usually the lower of each pair of tumblers in the pin tumbler cylinder mechanism. The upper are known as drivers.

Pipe key - A key with a flat bit and a hollow circular shank to locate on the drillpin. Used only on one-sided locks.

Plug - The part of the pin-tumbler cylinder mechanism or disc tumbler cylinder mechanism into which the key enters and which the key turns. It houses the pins of a pin tumbler cylinder mechanism or the discs and springs of a disc tumbler cylinder mechanism.

Pocket - The name of each segmental space in a lever which, while surrounding the bolt stump, allows the lever to rise and fall whether the lock bolt is in or out.

Postal handle - A letter plate with a pull handle.

Postal knocker - A letter plate with a pull handle, the latter specially adapted and used as a knocker.

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