rose window, large, stone-traceried, circular window of medieval churches. Romanesque churches of both England and the Continent had made use of the wheel window—a circular window ornamented by shafts radiating from a small center circle; and from this prototype developed the elaborate rose windows. The latter, in their full development, flourished especially in France, where they appear in practically every important Gothic cathedral, either over the center portal of the west front or on at least one of the transept ends. Stained glass was usually placed in them. The early examples, as on the west facade of the cathedral at Chartres (12th–13th cent.), were filled with plate tracery tracery, bands or bars of stone, wood, or other material, either subdividing an opening or standing in relief against a wall and forming an ornamental pattern of solid members and open spaces.
..... Click the link for more information. , pierced from a stone slab. With the perfection of bar tracery, the typical rose, as in the cathedral at Reims (13th–14th cent.) and in Notre-Dame de Paris (12th–14th cent.), was filled with numerous radiating bars and intermediate bars, joining to form pointed arches at the outer edge. In the final or flamboyant period the bars were arranged in wavy curves and more intricate patterns. This rich and closely packed tracery, as in the fine transept window of St. Ouen at Rouen, suggests the design of an open rose.

rose window

In Gothic architecture, a decorated circular window, often glazed with stained glass, that first appeared in mid-12th-century cathedrals. It was used mainly at the western end of the nave and the ends of the transept. The bar tracery of a High Gothic rose window consisted of a series of radiating forms, each tipped by a pointed arch at the outside of the circle. The rose windows of Notre-Dame de Paris are particularly noteworthy. In later Flamboyant-style tracery, the radiating elements consisted of an intricate network of wavy, double-curved bars.