Witch window

In American vernacular architecture, a witch window (also known as a Vermont window, among other names) is a window (usually a double-hung sash window, occasionally a single-sided casement window) placed in the gable-end wall of a house and rotated approximately 1/8 of a turn (45 degrees) from the vertical, leaving it diagonal, with its long edge parallel to the roof slope. This technique allows a builder to fit a full-sized window into the long, narrow wall space between two adjacent roof lines, where a window would not otherwise fit.

Witch windows are found almost exclusively in or near the U.S. state of Vermont, generally in the central and northern parts of the state. They are principally installed in farmhouses from the 19th century, and can be found less frequently in new construction.