- Muntins
In glazed lite assemblies, thin vertical and horizontal divider bars, which give the lite a multi-paned look. Muntins may be part of lite frames, and on the outside surface of the glass, or assembled between glass in insulated glass units.
- Multiple Extension Unit
In patio door assemblies, a fixed door panel in a separate frame, edge-joined to a patio door unit to add another glass panel to the installation.
- Mullion
A post or divider which runs from sill to frame top in multi-panel doors, or sidelite assemblies.
- Mull
A short term for mullion. Used to describe the edge-joining of two door units or sidelites together.
- Mortise-Type Lock
A lock-set, which is housed into a deep recess cut into the edge of a door.
- Mortise
A recess cut into the surface or edge of a part, usually for the purpose of housing hardware such as hinges, latch plates etc.
- Miter
An angled cut across the end of a lineal part, usually done to join with a similarly cut part at a corner. Most typically used in casing.