​ FENESTRATION (from O. Fr. fenestre, modern fenêtre, Lat. fenestra, a window, connected with Gr. φαίνειν, to show), an architectural term applied to the arrangement of windows on the front of a building, more especially when, in the absence of columns or pilasters separating them, they constitute its chief architectural embellishment. The term “fenestral” is given to a frame or “chassis” on which oiled paper or thin cloth was strained to keep out wind and rain when the windows were not glazed.