abb. maximum adjacent cut specification
magic number
n. for an SFIC, a value from which subtracting the control cut depth will result in the correct top pin size, or, subtracting the top pin size will result in the control cut depth
magnetic contact
n. an electrical switch activated by magnetic attraction or repulsion
magnetic latch
n. a latch which uses magnetic force to stay engaged with its strike
magnetic stripe
n. a thin layer of material consisting of oriented ferromagnetic oxide particles held together by a resin binder and bonded to a non-magnetic surface such as paper or plastic 
magnetically positioned pin
n. a pin tumbler requiring magnetic energy to position it, rather than springs or gravity
maid's master key
n. the master key in a hotel master key system given to the maid. It operates only cylinders of the guestrooms and linen closets in the maid's designated area.
maison key system
n. [from the French, meaning "house" key system] a keying system in which one or more cylinders are operated by every key (or relatively large numbers of different keys) in the system; e.g., main entrances of apartment buildings operated by all individual suite keys of the building
man door
n. a door designed to allow access by a person. It may be located in a wall, or in another, larger, door which has other purposes.
man trap
n. a sally port designed for pedestrian traffic
v. a dialing process typically used with combination locks to determine operational status of the lock, potential combinations or attempt to free the mechanism 
n. an opening method for mechanical combination locks which uses the tolerances of that lock to determine an opening combination
manipulation key
n. any key other than a correct key which can be variably positioned and/or manipulated in a keyway to operate a lock or cylinder
manipulation proof
n. a combination lock with features designed to prevent determining the combination without physical attack
manipulation resistant
n. a combination lock with features that prevent determining the combination without physical attack within a specific time limit 
manual dogging
n. 1. an exit device that requires a physical action to dog it, v. 2. using a wrench or a special key to dog an exit device
manufacturer reset code
n. in an electronic lock, a factory-set or user-set code or combination that will restore the factory default settings
master blank
n. a key blank used in a complementary keyway lock, on which only the master key combination is intended to be cut
master code
n. in an electronic lock, a factory-set or user-set combination that must be used before programming the lock
master disc
n. a special disc tumbler with multiple gates to receive a sidebar, see also "master pin" #1, see also "stepped tumbler".
master key
n. 1. a key which operates all the master keyed locks or cylinders in a group, each lock or cylinder usually operated by its own change key, 2. v. to combinate a group of locks or cylinders such that each is operated by its own change key as well as by a master key for the entire group, 3. n. an automotive key which operates all or most locks on a vehicle where there is also a valet key employed
master key changes
n. the number of different usable change keys available under a given master key
master key system
n. 1. any keying arrangement which has two or more levels of keying 2. a keying arrangement which has exactly two levels of keying
master keyed
adj. 1. of or pertaining to a cylinder or group of cylinders which are or are to be combinated so that all may be operated by their own change key(s) and by additional key(s) known as master key(s) 2. a warded lock whose warding has been designed to allow different hierarchies of keys to operate
master keyed only
adj. of or pertaining to a lock or cylinder which is or is to be combinated only to a master key
master lever
n. a lever tumbler which can align some or all other levers in its lock so that their gates are at the fence. It is typically used in locker locks.
master pin
n. 1. usually a cylindrical shaped tumbler, flat on both ends, placed between the top and bottom pin to create an additional shear line 2. a pin tumbler with multiple gates to accept a sidebar
master ring
n. a tube shaped sleeve located between the plug and shell of certain cylinders to create a second shear line. Normally the plug shear line is used for change key combinations and the shell shear line is used for master key combinations.
master ring lock/cylinder
n. a lock or cylinder equipped with a master ring
master wafer
n. a ward used in certain binary type disc tumbler key-in-knob locks, see also "master pin" #1, see also "stepped tumbler"
mat switch
n. a flat semi flexible device which opens or closes a circuit when rated pressure is applied
matrix format master keying
n. a method of generating combinations and assigning key symbols in a master key system through the use of a matrix
maximum adjacent cut specification
n. the maximum allowable difference between adjacent cut depths
maximum compound cut specification
n. the maximum allowable difference between the different depths of a compound cut
maximum opposing cut specification
n. the maximum allowable depths to which opposing cuts can be made without breaking through the key blade. This is typically a consideration with dimple keys.
Abb. Maximum Compound Cut Specification
media safe
n. a security container designed to maintain an internal temperature at which multi-media will remain reliable for a set period of time
medium stile
adj. pertaining to an aluminum or hollow metal door with a stile generally between 3-1/4 and 4-1/4 inches wide
mesh change
n. a type of hand change combination lock wheel, consisting of an inner and outer wheel which engage each other by intermeshing teeth
metal desk lock
n. a cabinet lock with a vertically sliding bolt located at the rear of the cylinder
meter lock
n. 1. a padlock whose shackle consists of a single removable post, designed for locking utility meters or valves. 2. any of several small devices specifically designed to lock utility meters or valves and which require either a key or special wrench for removal
milling cutter
n. a key machine cutter with relatively coarse pitch teeth as opposed to a rotary file cutter
milling runout
n. the distinctive shape caused by the curved surface of milling cutters at the bow end of a key blade
1. adj. of or pertaining to a key which has been cut incorrectly 2. n. a mis-cut key
abb. master key
abb. modified key coding system
abb. master keyed
MK'd only
abb. master keyed only
MK section
abb. master key section
abb. maximum opposing cut specification
modified key coding system
n. a modification of the standard key coding system, in which the TMK of a system with three or more levels of keying has a single letter name, and keys at lower levels are named following SKCS conventions
Mogul cylinder
n. a pin tumbler cylinder with a diameter of 2.0", whose pins, springs, key, etc. may also be proportionally increased in size. It is frequently used in prison locks.
monitor pin
n. a device that requires a specific mechanical feature on a key, such as a protrusion or the lack of a cut in a specific area, to allow the lock to operate
monitored door
n. a door equipped with a device that reports, or reports and records, the operational status of the door, lock or other hardware
mop plate
n. a narrow plate fixed to the bottom of a door for protection against soiling from a mop; similar to a kickplate
1. v. to prepare by removing stock material from the edge of a door, drawer, frame or opening to create a recess which allows the flush fit or insetting of relevant lock or other hardware, 2. n. the cavity prepared by mortising, 3. adj. of or pertaining to a locking device designed to fit in a mortise preparation
mortise cylinder
n. a threaded cylinder typically used in mortise locks of American manufacture
mortise exit device
n. an exit device designed for mortise installation
mortise lockset
n. a lockset the case of which is designed to fit in a mortise in the edge of a door or drawer
motion alarm lock
n. a security locking device which audibly alerts upon sensing motion
movable key insert
n. any device pressed into or connected to a key blank, such that its presence and movement are required for proper key operation, and the absence of which results in a lockout
n. a mechanical, electronic or electro-mechanical timer, designed to inhibit the final unlocking of a combination lock or timelock
abb. manipulation proof
abb. manipulation resistant
abb. Maximum Security. A trademark of the Adams Rite Manufacturing Co.
n. a vertical center post in the frame of a pair of doors
multi-color finish
adj. of or pertaining to a lockset whose finish is different for different trim components on one side of a door
multi-part key
n. any bit key not able to be duplicated by a single casting process
multi-point lock
n. a lock which has more than one bolt which are thrown and withdrawn simultaneously, often in more than one direction
multi-section key blank
n. a key section which enters more than one, but not all keyways in a multiplex key system
multiple gating
n. a means of master keying by providing a tumbler with more than one gate
multiplex key blank
n. any key blank which is part of a multiplex key system
multiplex key system
n. 1. a series of different key sections which may be used to expand a master key system by repeating bittings on additional key sections. The keys of one key section will not enter the keyway of another key section. This type of system always includes another key section which will enter more than one, or all of the keyways. 2. a keying system which uses such keyways and key sections
n. a structural member in a door or window used to divide a large lite into smaller ones 
mushroom pin
n. a pin tumbler, usually a top pin, which resembles a mushroom. It is typically used to increase pick resistance
mykey chart
n. a matrix depicting user requested cross keying by listing keys along one axis and openings along the other. So named because it is frequently accompanied by the statement "My key goes here and here and here."


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Appendix

This listing of the Locksmith Dictionary is courtesy of