-–-Part-3-(M–Z).jpg "The Complete Door & Lock Glossary (A–Z) – Part 3 (M–Z)")
Understanding Door and Lock Terminology for Homeowners
Welcome to the final part of our Complete Door & Lock Glossary. This section covers terms from M to Z, including lock manufacturers, security standards, lock types, door hardware, key systems and many of the specialist components found in modern uPVC, composite, timber and French doors.
By the end of this three-part guide, you'll have one of the most comprehensive homeowner references available for understanding modern doors and locks.
M
Maco
Maco
What it is
An Austrian manufacturer of multipoint locking mechanisms, window hardware and door components used throughout Europe and the UK.
Why it matters
Maco mechanisms are fitted to many residential doors. Replacement gearboxes are often available, but accurate measurements are essential before ordering parts.
Commonly Found On
- uPVC doors
- Composite doors
- French doors
Related Complete Guides
- Complete Guide to Multipoint Locking Systems
- A–Z of Multipoint Lock Manufacturers
- Complete Guide to Door Locks
Master Suite (Master Key System)
What it is
A keying system where one master key operates multiple locks while each individual lock also has its own unique key.
Why it matters
Master key systems provide controlled access while allowing authorised users to open several locks with a single key.
Commonly Found On
- Apartment buildings
- Offices
- Schools
- Commercial premises
Related Complete Guides
- A–Z of Euro Cylinders
- Complete Guide to Door Locks
Mila
What it is
A manufacturer of door hardware including handles, hinges and multipoint locking systems.
Why it matters
Mila hardware is commonly found on uPVC doors throughout the UK.
Milamaster
What it is
A range of multipoint locking mechanisms manufactured by Mila.
Why it matters
Several versions exist with different gearboxes and locking point layouts, making correct identification essential.
Commonly Found On
- uPVC doors
- Composite doors
Related Complete Guides
- Complete Guide to Multipoint Locking Systems
- A–Z of Multipoint Lock Manufacturers
Millenco
What it is
A British manufacturer producing multipoint locks, replacement gearboxes, Euro cylinders, handles and security hardware.
Why it matters
Millenco also manufactures compatible replacement parts for many obsolete locking systems.
Commonly Found On
- uPVC doors
- Composite doors
Related Complete Guides
- A–Z of Multipoint Lock Manufacturers
- Complete Guide to Door Locks
- Complete Guide to Multipoint Locking Systems
Mortice Deadlock
What it is
A mortice lock operated solely by a key, without a latch.
Why it matters
Often fitted as a secondary security lock on timber entrance doors.
Commonly Found On
- Timber front doors
- Timber back doors
Related Complete Guides
- Complete Guide to Door Locks
- Complete Guide to Home Door Security
Mortice Sashlock
What it is
A mortice lock combining a spring latch and a deadbolt within one lock case.
Why it matters
One of the most common locking systems used on traditional timber entrance doors.
Commonly Found On
- Timber entrance doors
Related Complete Guides
- Complete Guide to Door Locks
- Complete Guide to Home Door Security
Mushroom Cam (Mushroom Locking Point)
What it is
A mushroom-shaped locking point that engages with a mushroom keep.
Why it matters
Provides excellent resistance against levering attacks.
N
Nemef
What it is
A Dutch manufacturer of locks and door hardware.
Why it matters
Commonly found on imported European doors.
Nightlatch
What it is
A surface-mounted lock that automatically latches when the door closes.
Why it matters
Often referred to as a "Yale Lock."
Non-Deadlocking Nightlatch
What it is
A nightlatch that can be opened from outside by turning the handle when unlocked.
Why it matters
Common on internal communal doors.
O
Offset Handles
What they are
Door handles where the internal and external levers are positioned at different heights.
Why they matter
Replacement handles must match the original offset design to fit and operate correctly.
Commonly Found On
- Composite doors
- Some uPVC doors
Related Complete Guides
- A–Z of uPVC & Composite Door Handles
- Complete Guide to Door Components & Hardware
Overnight Lock
What it is
A locking arrangement designed to provide additional security while the property is occupied.
Why it matters
Some overnight locking systems allow secure internal operation without affecting emergency exit.
Commonly Found On
- Composite doors
- Apartment entrance doors
Related Complete Guides
- Complete Guide to Door Locks
- Complete Guide to Home Door Security
- Why Doors Fail
P
Panic Lock
What it is
A locking system allowing immediate escape from inside without using a key.
Why it matters
Often fitted to emergency exits and communal buildings.
Passive Door
What it is
The secondary leaf of a pair of French or double doors that normally remains secured until required.
Why it matters
The passive door is held closed by shoot bolts or a dedicated slave locking mechanism.
Commonly Found On
- French doors
- Double composite doors
Related Complete Guides
- Complete Guide to French Door Security, Maintenance and Repairs
- Complete Guide to Multipoint Locking Systems
Passive Door Slave Lock
What it is
The locking mechanism fitted to the passive French door.
Why it matters
Works together with the active door.
PAS 24
What it is
A recognised British security standard used to test complete doorsets against methods of forced entry.
Why it matters
Many new doors are certified to PAS 24 as evidence of their security performance.
Commonly Found On
- Composite doors
- uPVC doors
- Timber doors
Related Complete Guides
- Complete Guide to Home Door Security
- Understanding Door Lock Security Standards
Pencil Hinge
What it is
A slim adjustable hinge commonly found on older uPVC doors.
Why it matters
Allows limited door adjustment.
R
Rain Deflector
What it is
A weatherproof strip fitted above the door.
Why it matters
Helps divert rainwater away from the door.
Rebated Door Kits
What they are
Special components allowing locks, handles and cylinders to operate correctly on rebated French doors.
Why they matter
They ensure both door leaves align and lock securely.
Commonly Found On
- French doors
Related Complete Guides
- Complete Guide to French Door Security, Maintenance and Repairs
- Complete Guide to Multipoint Locking Systems
Repair Plates
What they are
Metal reinforcing plates used when fitting replacement handles.
Why they matter
Cover damaged fixing holes and strengthen older doors.
Repair Screws
What they are
Replacement screws supplied for fitting new locks and handles.
Reversing Latch
What they are
Replacement fixing screws supplied for fitting locks, handles and door hardware.
Why they matter
Using the correct screws helps ensure components are fitted securely.
Commonly Found On
- All door types
Related Complete Guides
- Complete Guide to Door Components & Hardware
Rim Cylinder
What it is
The cylinder fitted to a traditional nightlatch.
Roller
What it is
A rounded locking point that compresses the door against its seals.
Why it matters
Improves weatherproofing while contributing to security.
Roller Keep
What it is
The keep receiving the roller.
Rollerbolt Nightlatch
What it is
A nightlatch using a roller instead of a traditional latch.
Roto
What it is
A major European manufacturer of multipoint locking systems and window hardware.
Why it matters
Roto mechanisms are widely used throughout Europe and the UK.
Commonly Found On
- uPVC doors
- Composite doors
Related Complete Guides
- A–Z of Multipoint Lock Manufacturers
- Complete Guide to Multipoint Locking Systems
S
Sash Jammer
What it is
An additional security device preventing doors opening even if the main lock is defeated.
Scandinavian Cylinder
What it is
A cylinder manufactured to Scandinavian locking standards rather than the Euro profile.
Why it matters
Common on imported Scandinavian doors.
Related Complete Guides
- A–Z of Euro Cylinders
Screw Centres
What they are
The distance between the handle fixing screws.
Secured by Design
What it is
A police-backed initiative promoting products that meet recognised security standards.
Why it matters
Products carrying the Secured by Design accreditation have been independently assessed for security performance.
Related Complete Guides
- Complete Guide to Home Door Security
- Understanding Door Lock Security Standards
Securistyle
What it is
A manufacturer of multipoint locking systems.
Shoot Bolts
What they are
Steel bolts extending into the head and threshold of the frame.
Why they matter
Common on French doors.
Single Spindle
What it is
A locking system using one spindle to operate both handles.
Slave Lock
What it is
Another name for the locking mechanism fitted to the passive French door.
Sobinco
What it is
A Belgian manufacturer of premium door hardware.
Sold Secure
What it is
An independent testing organisation certifying security products.
Split Spindle
What it is
An independent testing organisation that certifies security products.
Why it matters
Sold Secure certification demonstrates resistance to recognised attack methods.
Related Complete Guides
- Understanding Door Lock Security Standards
- Complete Guide to Home Door Security
Sprung Handles
What they are
Door handles containing internal return springs.
Why they matter
They reduce strain on the gearbox and help extend the life of the locking mechanism.
Related Complete Guides
- A–Z of uPVC & Composite Door Handles
- Complete Guide to Door Components & Hardware
SS312 Diamond
What it is
One of the highest independent security ratings available for Euro cylinders.
Why it matters
Provides excellent resistance against snapping, drilling, picking and bumping.
Related Complete Guides
- A–Z of Euro Cylinders
- Complete Guide to Euro Cylinder Door Locks
Surelock
What it is
A manufacturer of replacement locking systems.
T
Thumb Turn Cylinder
What it is
A Euro cylinder with a thumb turn on the inside and a key on the outside.
Why it matters
Allows quick locking and unlocking from inside without using a key.
Related Complete Guides
- A–Z of Euro Cylinders
- Complete Guide to Euro Cylinder Door Locks
TS007 1 Star
What it is
A security-rated Euro cylinder.
Why it matters
Designed to work with TS007 2 Star security handles to achieve enhanced protection.
Related Complete Guides
- Understanding Door Lock Security Standards
- Complete Guide to Euro Cylinder Door Locks
TS007 2 Star
TS007 2 Star
What it is
A security-rated door handle.
Why it matters
When combined with a TS007 1 Star cylinder, it provides an overall 3 Star level of protection.
Related Complete Guides
- A–Z of uPVC & Composite Door Handles
- Complete Guide to Euro Cylinder Door Locks
- A–Z of Burglary Prevention
TS007 3 Star
What it is
A standalone high-security Euro cylinder.
Why it matters
Provides excellent protection against lock snapping and other common methods of attack.
Related Complete Guides
- A–Z of Euro Cylinders
- Complete Guide to Euro Cylinder Door Locks
- Complete Guide to Home Door Security
U
UCEM
What it is
A manufacturer of locking systems and door hardware.
V
Vicaima
What it is
A manufacturer of internal and external doors, including fire doors.
Vitawin
What it is
A manufacturer of window and door hardware.
W
Weather Seal
What it is
A rubber or foam seal preventing draughts and water ingress.
WERU
What it is
A German manufacturer of premium doors and windows.
Wilka
What it is
A German manufacturer of locks, cylinders and master key systems.
Winkhaus
What it is
One of Europe's largest manufacturers of multipoint locking mechanisms, gearboxes and security hardware.
Why it matters
Winkhaus has produced many different locking systems over the years, making accurate identification essential before ordering replacement parts.
Commonly Found On
- uPVC doors
- Composite doors
- French doors
Related Complete Guides
- A–Z of Multipoint Lock Manufacturers
- Complete Guide to Multipoint Locking Systems
- Complete Guide to Door Locks
Y
Yale
What it is
What it is
One of the world's best-known manufacturers of residential locks and security products.
Why it matters
Yale manufactures nightlatches, Euro cylinders, multipoint locking systems, smart locks and door hardware. Although many people refer to any nightlatch as a "Yale lock", Yale is a brand rather than a type of lock.
Commonly Found On
- Timber doors
- uPVC doors
- Composite doors
Related Complete Guides
- Complete Guide to Door Locks
- A–Z of Euro Cylinder Brands
- Complete Guide to Home Door Security
Z
Zinc Alloy
What it is
A metal alloy commonly used to manufacture door handles, escutcheons, letterplates and other door furniture.
Why it matters
Quality zinc alloy provides a good balance of strength, corrosion resistance and durability, making it one of the most widely used materials for modern door hardware.
Commonly Found On
- uPVC doors
- Composite doors
- Aluminium doors
Related Complete Guides
- Complete Guide to uPVC & Composite Door Handles
- Complete Guide to Door Components & Hardware
Related Complete Guides
Continue Learning About Doors & Locks
If you found this glossary useful, these guides explain each subject in greater detail.
- Complete Guide to Door Locks
- Complete Guide to Multipoint Locking Systems
- Complete Guide to Door Components & Hardware
- Complete Guide to Euro Cylinder Door Locks
- A–Z of Common Lock Faults
- A–Z of Door Problems
- A–Z of uPVC & Composite Door Handles
- Complete Guide to Door Alignment & Lock Performance
- Complete Guide to Home Door Security
- A–Z of Euro Cylinders
- A–Z of Multipoint Lock Manufacturers
Conclusion
Modern doors are made up of hundreds of individual components, security features and specialist terms that can be confusing for homeowners. Understanding this terminology makes it much easier to identify faults, discuss repairs with a locksmith and choose suitable replacement parts when upgrades become necessary.
Whether you're maintaining a uPVC, composite, timber or French door, this Complete Door & Lock Glossary provides a practical A–Z reference covering the terms most commonly used throughout the industry. Use it whenever you need to identify a component, understand a repair recommendation or learn more about how modern door locking systems work.
Further Reading
The Complete Door & Lock Glossary (A–Z) – Part 1 (A–D). /
The Complete Door & Lock Glossary (A–Z) – Part 2 (E–L)
