Symmetrical Trefoils are particularly popular as warning symbols. If a box containing hazardous material is moved around and shifted into different positions, it is still easy to recognize the symbol. Easily stenciled symbols are also favored.

While the green trefoil is considered by many to be the symbol of Ireland, the harp has much greater officially recognized status. Therefore shamrocks generally do not appear on Irish coins or postage stamps.

A trefoil is also part of the logo for Adidas Originals, which also includes the iconic three stripes.

A trefoil formation is a cross-sectional arrangement of electrical cables that minimises electrodynamic forces during fault conditions. Also, the magnetic field of each phase conductor in a 3-phase system is negated when the other two phase conductors are nearby to form a trefoil.