Illustrated Architecture Dictionary.......... Illustrated FURNITURE Glossary
TREE foil, tref oil
A three-lobed circle or arch formed by cusping
Used in windows and arches
In French, "foil" means "leaf." The number of foils involved is indicated by a prefix, e.g. trefoil, quatrefoil, cinquefoil, sexfoil, multifoil
Found in Gothic Revival, Tudor Revival styles
A trefoil combined with an equilateral triangle was a moderately common symbol of the Christian Trinity during the late Middle Ages in some parts of Europe.
A stylized shamrock,
symbol of perpetuity, with the three leaves representing the past, present and future. It is also sometimes a symbol of fertility and abundance.
In Christian contexts it is used as a symbol for the Holy Trinity. As such it is often placed within a circle.
An architectural term for an arrangement of three interconnecting arcs; at each intersection there is a cusp.
In furniture the motif (pattern) was often applied to pierced arches and trefoil feet.
Examples from Buffalo: