Trefoil (from Latin
trifolium, three-leaved plant, French
trèfle,
German
Dreiblatt and
Dreiblattbogen) 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,
one of the earliest examples being in the plate tracery at Winchester (
1222—
1235);
see
Quatrefoil[?].
Larger Birdsfoot trefoil
