• (n.) A window pierced in a roof, and so set as to be vertical while the roof slopes away from it. Also, the gablet, or houselike structure, in which it is contained.
window placed vertically in sloping roof
Window that projects from a sloping roof 
[n] - the window in a gabled extension built to accommodate a window
The window in the vertical end of a dormer.
window placed vertically in sloping roof
A window housed in a gable or similar structure affixed to the sloping part of a roof, providing natural light and ventilation to the rooms beneath the roof. See also: Window.