The large circular stained-glass window common in Gothic cathedrals is called a rose window. Its radiating stone tracery divides the circle into segments that can be filled with richly colored glass.
Rose windows became especially characteristic of Gothic churches in northern France. Early examples developed from simpler circular or “wheel” windows, while later designs became increasingly elaborate, with repeated lobes, spokes, and geometric patterns. The Abbey Church of Saint-Denis is associated with the early Gothic use of stained glass in this form during the 12th century.
A rose window was both architectural and symbolic. It admitted colored light into the church while often presenting biblical scenes, saints, or symbolic designs. Major cathedrals frequently placed one on the west façade or in a transept, where it could serve as a dramatic visual focus.
Common mix-ups involve the terms oculus and wheel window. An oculus is simply a circular opening, often without tracery, while a wheel window generally has straightforward radial spokes. “Catherine window” is another name, referring to Saint Catherine of Alexandria and her wheel of martyrdom. “Triforium” and “lancet,” by contrast, describe different architectural features and window shapes.