- Mullion: The vertical or horizontal divisions or joints between single windows in a multiple window unit.
- Muntin: A pattern of grids that are placed in-between two pieces of glass for decorative purposes.
- Operator: A metal arm and gear which allows for easy operation or closing of projecting windows.
- Outer frame member: The exterior protruding portion of a window frame which has no exterior casing.
- Palladian window: A large, arch-top window flanked by smaller windows on each side.
- Panel: Usually refers to the separate panel or panels in a door frame.
- Passive solar collector: Any glazed area in the walls or roof of a building pointed to the south to take maximum advantage of the sun's heat without a mechanical (or active) method of storage or distribution of the heat.
- Picture frame casing: The use of casing on all four sides of the interior of a window, replacing the stool and apron at the sill. Also know as full-bound casing.
- Pivot: A mode of operation for ventilating windows which generally means the sash pivots on a central axis and turns 90 or more degrees.
- Rafter: Structural members of a roof that support the roof load and run from the ridge to the eaves (overhang).
- Rails: The horizontal members of a window sash or door panel.
- Rough opening: The opening left in a frame wall to receive a window or door unit.
- Rough sill: The horizontal rough framing member, usually two inches by four inches, which forms the bottom of the rough opening. It is toe-nailed into the jack studs and is supported by cripples.
