Learn the Window Lingo

Window Glossary


American Architectural Manufacturers Association: A national trade association that establishes voluntary standards for the window and door industry.

Acrylic (plastic)

A non-crystalline thermoplastic with dependable weather and shatter resistance, and optical clarity; sometimes used for glazing.


To provide an extremely hard non-corrosive oxide film on the surface of aluminum, by electrolytic action. Anodic coatings may be transparent, varying shades of silver, gray, or brown, or colors may be incorporated by the use of dyes.


An inert, colorless, and harmless gas injected in the airspace of an insulating unit, to improve energy efficiency. Argon is less conductive to heat than air, which aids in the energy efficiency of the product.

Awning Window

A type of window with a top-hinged sash that swings out at the bottom, allowing fresh air in while keeping other elements out.


A mechanical device used in vertically operating windows that counter-balances the weight of the sash during opening and closing.

Basement Window

A sash unit, similar to an awning, used for basement or cellar window openings. Products may include screens and provisions for emergency evacuation from the basement area.

Bay Window

A type of window consisting of a central picture window flanked by a pair of narrow casement windows set at an angle providing a panoramic view.


A strip of metal, vinyl, or wood used around the periphery of a pane of glass to secure it in a frame or sash.  A strip of sealant, such as caulking or glazing compound.


A small piece of neoprene or other suitable material used to position the glass in a frame.


Material used to support a replacement windowsill and prevent it from rotating.

Bow Window

A type of window made of equal-sized casement or picture units in a gentle outward curve, which allows for a wider view and more living space.

Casement Window

A type of window with a side-hinged sash that opens like a door and is the best window for catching breezes and crosswinds. The sash is usually operated by a roto-operator or handle.

Double Hung Window

A vertically operated window consisting of two sashes operating in a rectangular frame. Both the upper and lower halves can be slid up and down and usually use a counter balance mechanism to hold the sash in place.


The measure of an object’s ability to radiate heat. Emissivity varies from 0 (no emitted infrared) to 1 (100% emitted infrared). The lower the emissivity, the more energy efficient a product is.


A type of paint that gives a glossy appearance.


All the windows and doors that are used in a particular project.


The enclosing structure of a window or door that consists of a head, jambs and sill into which sash or door panels fit.

Glazing (verb)

The installation of glass into a window or door sash.

Geometric Shape

Geometric shape windows can be made in a variety of custom shapes and sizes.

Glazing (noun)

The panel that is inserted into a sash.

Glazing Bead

A molding or stop along the inside perimeter of the frame that assists in holding glass in place.


Decorative fixed inserts for windows or doors that add a traditional touch.


The main horizontal member forming the top of the window or door frame.


A device on which a window or door may turn or swing, to open and close.

Horizontal Sliding Window

A window where one or more panels slide horizontally. These windows consist of an operable sash in a sealing frame.

Insulating Glass

Two or more pieces of glass spaced apart and sealed to form a single-glazed unit with an air space between. Heat transmission through this type of glass may be as low as half that without such an air space.


Construction materials used for protection from sound, heat, cold or fire. Air, argon or krypton gas spaces between panes of glass provide insulation.


A set of meeting rails, which when engaged with one another keep a sash or door panel from moving past a certain point.


Vertical, or side members of the window or door mainframe.

Laminated Glass

Two or more glass panels with an inner layer of transparent plastic to which the glass adheres if broken. This process produces glass four times more impact resistant than non-laminated glass.

Lift Rail

A rail in a vertical window used to raise and lower the operable sash.


The device on a window or door that secures it in a closed position.


A coating that has a reduced ability to radiate heat energy.

Marine Type Glazing

A glazing system that begins by wrapping the full perimeter of the glass unit with a soft vinyl channel that serves to cushion the glass, as well as provide positive protection from water.

Meeting Rail

The part of an operating glass door or window where two panels meet and create a weather barrier.


An intermediate-connecting member used as a means to “join” two or more window products together in a single rough opening.

Muntin Bar

A decorative addition that divides a glass panel into smaller sections.

Mounting Fin

An integral extension of a window frame, which generally laps over the conventional stud construction, through which fasteners are driven to secure the frame in place.


National Fenestration Rating Council: measures and compares the energy components of windows and doors.

Obscure Glass

Mainly used for decoration, diffusion or privacy. The design is pressed into the glass during the rolling process.


A component or handle that is used to move, pivot or to adjust the position of an operable sash, ventilator or panel in a window or door assembly.


A framed sheet of glass.


The individual moving component of a sliding door or window. Products typically come in 2-, 3-, or 4-panel configurations.


Panning refers to the outside cosmetic trim that can extend around the complete perimeter of the window opening. It is most commonly used in replacement projects and is used to cover up old window material, such as wood or steel.


The direct process of heat transfer through space by means of electromagnetic waves. Energy in the form of rays of light is transferred from body to body without heating the intermediate air.


A horizontal surrounding edge of a sash, ventilator or panel.


Apparatus inserted into window or door opening to cover any inconsistencies and simplify installation.


A window opening device that has a handle to crank open a window.


The portion of a window which fits into the mainframe. Depending on the type of window, sashes may be either fixed (non-moveable) or operational (moveable).


A product used with a window or door, consisting of a four-sided frame surrounding a mesh of wire or plastic material used to keep out insects and other outdoors elements. The screen can be fixed in place or it can be rolled side-to-side as on a sliding glass door.


The main horizontal member forming the bottom of the frame of a window or door.

Single Glazing

The use of single thickness of glass in a window or door.

Single Hung Window

Single hung windows are vertically operating windows in which the sash weight is offset by a counterbalancing mechanism. The single hung window features a stationary top and a movable bottom sash. One or more locking devices are furnished to secure the sash in the closed position.

Sliding Glass Door

Sliding glass doors consist of one or more panels contained in a frame, which is designed to allow one or all panels to move in a horizontal direction. All door panels can be operational, or some can remain fixed.


Material used to maintain separation between glass surfaces of insulated glass units.


The upright or vertical surrounding edge of any sash, ventilator or panel.

Tempered Glass

Glass that has been treated at high temperatures to increase its overall strength. If broken, tempered glass will fracture rather than shattering. Tempered glass is roughly four times stronger than non-tempered glass.

Tinted Glass

Glass is colored to help produce light reducing and/or heat absorbing glass particles.


The invisible rays of the spectrum, which are outside of the visible spectrum at its violet end. UV rays are found in everyday sunlight and can cause fading or chalking of dark paint finishes.


Polyvinylchloride (PVC) material that can be either rigid or flexible, used in glazing channels and weathering of both windows and doors.

Warm Edge Spacers

Insulating spacers that help insulated glass units achieve better thermal performance.


Thin sections of material used to prevent air leakage, water penetration or both around operable windows and doors.


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