Trefoil

A trefoil () is a graphic form composed of the outline of three overlapping rings, used in architecture, Pagan and Christian symbolism, among other areas. The term is also applied to other symbols with a threefold shape. A similar shape with four rings is called a quatrefoil. 'Trefoil' is a term in Gothic architecture given to the ornamental foliation or cusping introduced in the heads of window-lights, tracery, and panellings, in which the centre takes the form of a three-lobed leaf (formed from three partially overlapping circles). One of the earliest examples is in the plate tracery at Winchester Cathedral (1222–1235). The fourfold version of an architectural trefoil is a quatrefoil. A simple trefoil shape in itself can be symbolic of the Trinity, while a trefoil combined with an equilateral triangle was also a moderately common symbol of the Christian Trinity during the late Middle Ages in some parts of Europe, similar to a barbed quatrefoil. Two forms of a trefoil combined with a triangle are shown below: File:Trefoil-Architectural-Equilateral-Triangle-outlined.svg|alt=The outline of three interlocking circles with an equilateral triangle in the centre.|Outlined File:Trefoil-Architectural-Equilateral-Triangle-interlaced.svg|alt=Three interlocking circles with a triangle in the centre, the full, interlocking lines of each now shown.|Interlaced A dove, which symbolizes the Holy Spirit, is sometimes depicted within the outlined form of the trefoil combined with a triangle. In architecture and archaeology, a 'trefoil' describes a layout or floor plan consisting of three apses in clover-leaf shape, as for example in the Megalithic temples of Malta. Particularly in church architecture, such a layout may be called a "triconchos". File:Evolution du plan des temples copie.jpg|alt=A diagram of six examples of evolving temple floor plans, evolving clockwise, labelled {{lang|fr|Typologie des temples}} ("temple typology"). The floor plans evolve from small, simple rooms to much larger and more elaborate constructions.