Trefoil (from Latin trifolium, "three-leaved plant", French trèfle, German Dreiblatt and Dreiblattbogen)'s a graphic form composed of the outline of three overlapping rings used in architecture and Christian symbolism. The term's also applied to other symbols of three-fold shape. Architecture Trefoil's 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-… (More on Trefoil)