Trefoil

Trefoil (from Latin trifolium, "three-leaved plant", French trèfle, Italian trifoglio, German Dreiblatt and Dreiblattbogen, Dutch klaver, "clover", same as clubs) is a graphic form composed of the outline of three overlapping rings used in architecture and Christian symbolism. The term is also applied to other symbols of three-fold shape.

Trefoil is a term in Gothic architecture given to the ornamental foliation or cusping introduced in the heads of window-lights, tracery, panellings, etc., in which the center 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 (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. Two forms of this are shown below:

Outlined

Interlaced

A dove, symbolic of the Holy Spirit, is sometimes depicted within the outlined form of the trefoil combined with a triangle.

In architecture and archaeology, trefoil describes a layout or floorplan 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".

Evolution of layout of Maltese Megalithic temples; Skorba (upper right) has a typical trefoil plan

Triconchos

The heraldic trefoil is a stylized clover. It should not be confused with the figure named in French heraldry tiercefeuille, which is a stylized flower with three petals. It differs from the heraldic trefoil in being not slipped. It could be translated as threefoil.

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