Illustrated Architecture Dictionary


Parts of a window

The head is the main horizontal part forming the top of the window frame.
Jambs are the main vertical parts forming the sides of a window frame.
A sill is the main horizontal part forming the bottom of the frame of a window.

Types of glass

Types of windows

Window Treatments

Band/ribbon: One of a horizontal series of three windows or more, separated only by mullions, that form a horizontal band across the facade of a building In the US, most commonly found in buildings erected after 1900.

Casing: The exposed trim molding, framing, or lining around a door or window; may be either flat or molded.

A wide fixed pane with narrow movable sash windows flanking it. 

Double-hung: A window having two vertically sliding sashes, each designed to close a different half of the window.

Double window:
two windows, side by side, which a single architectural unit

Elliptical: See fanlight

Windows that do  not open, e.g.: casement, picture

Frame: An open structure or rim for encasing, holding or bordering

French: A casement window extending down to the floor; also called a French door

Grille: An ornamental arrangement of bars to form a screen or partition, usually of metal, wood, stone, or concrete, to cover, conceal, decorate, or protect an opening

Hopper: A  bottom-pivoting casement window that opens by tilting vertically, typically to the inside.

"A hopper window is a single style window similar to a casement window in that they both are hinged for opening, rather than slide open. A hopper window is hinged on the bottom and opens inward from the top. Though a hopper window can come in a variety of sizes, the hopper window is a common style window in small areas and openings, such as basements and bathrooms." - Wise Geek (May 2012)

A crescent or semicircular window or wall panel framed by an arch or vault. Commonly called a "half-moon window."

Order: with columns and entablature

Pane: One of the divisions of a window or door, consisting of a single unit of glass set in a frame

Quarter round

A bar extending horizontally between supports

Ribbon - See
"Band" above

Sash: Any framework of a window; may be movable or fixed; may slide in a vertical plane (as in a double-hung window) or may be pivoted (as in a casement window). The development of counterweighted vertically sliding sashes in the 1670s eliminated the need for for mullions and transoms while allowing much larger areas of glass to be moved. By 1700 sashes were common.

The horizontal bottom member of a window frame. A window sill is the surface at the bottom of a window. Window sills serve to hold the window or glass in place and also provide a mechanism - like a course - for the shedding of rain water away from the wall directly below the window.


Splayed: A window whose frame is set at an angle with respect to the face of the wall

Stained-glass window: A window whose glass is colored. Example from Karpeles Manuscript Museum

One of the upright structural members of a window frame, at the outer edge

An encircling border or decorative frame

Treble sash: A window having three vertically sliding sashes, one above the other; each of which closes a different part of the window; occasionally found in America in the late 18th and early 19th centuries in large houses having very high ceilings. Compare with three-part window

Triangular: Window shaped like a triangle

Tripart / triple / three-part window
: A window having a wide rectangular sash at its center and a narrower sash on each side; sometimes all three sashes are of the same height and are in the same plane; essentially a Palladian window with the rounded head of the center sash sometimes lopped off at the top.  Found in many Greek Revival style homes, this type of window was introduced in America in about 1785. Compare with treble sash and Chicago window

Triple-hung: A window having three vertically sliding sashes, each designed to close a different third of the window.  A double-hung window with two sashes can move up and down in the window frame. ... Triple- and quadruple-hung windows are used for tall openings, common in New England churches.

Twin lancet windows under pointed arch, crowned by a quatrefoil: lancet window ... quatrefoil

Page by
Chuck LaChiusa
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