Trefoil

Architecture

Ornamentation

'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:

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

Architectural layout

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".