A roundel refers to any ornamental disk enclosed in a circular shape. It can be made of various materials such as metal, stone, or glass and is often used as a decorative element in architecture, design, or art. Roundels can feature intricate patterns, motifs, or symbols, and are commonly seen in stained glass windows, ceiling decorations, or as standalone decorative pieces. Other terms such as rosette, medallion, or patera can also refer to similar circular ornaments used in decorative arts and architecture. A rosette, a medallion, a patera, or any ornamental disk enclosed in a circular shape.