Tracery

In architecture, Tracery is the stonework elements that support the glass in a Gothic window. The term probably derives from the 'tracing floors' on which the complex patterns of late Gothic windows were laid out.

Read more about Tracery:  Plate Tracery, Bar Tracery, Blind and Open Tracery, Tracery Patterns and The Phases of Gothic, Tracing Floors and ├ępures