M
Main FrameThe head, sill and jambs sections of a window.
Make SizeThe exact measurement (tip to tip).
Marine GlazingThe term comes about because this type of glazing is often used in boats and other marine applications. (Same as Channel Glazing or Wrap Around Glazing)
Masonry OpeningThe space in a masonry wall left open for windows or door.
Mechanically Fastened FrameRefers to frames fastened with screws.
Meeting RailCross member of a window or sliding glass door where the sash comes together with an interlocking action. (Same as Mid-Rail)
Meeting StileThe vertical section of a pair of sash that meet when the sash are closed.
MeshFabric made of either fiberglass or aluminum, used in the making of screens.
Mid-RailSame as Meeting Rail.
Mill FinishUncoated aluminum as it comes from the mill. (See Finish)
MillworkGenerally all building components of finished wood that are made in a woodworking plant or planning mill. Includes doors, window sashes, door frames and window frames as well as stair components, trim moldings, mantels and wainscot panels.
MortiseA slot or rectangular cavity cut into a piece of wood to receive another part.
Mortise and TenonA strong wood joint made by fitting together a mortise in one board and a matching projecting member (tenon) in the other.
Moving VentThe operating sash of a window or the operating panel of a sliding glass door.
MullA shorten version for Mullion. Also used as a verb, as in "to mull" two windows together.
MullingThe act of attaching two or more windows or a door and transom units together.
MullionA wood, metal, or vinyl part used to structurally join two window or door units.
MuntinA part of a window that divides a light of glass into smaller sections. A true muntin (the first "n" in "muntin" is silent) actually separates the pieces of glass. Insulated glass usually uses internal muntins, which only appear to divide the glass into smaller lights. Muntins are normally either vertical or horizontal although diagonal and curved are also used. SWISCO commonly uses the term grid. See Divided Light, and grid.
