Quatrefoil knot (Accepted)

The “quatrefoil knot” is a closed loop with four lobes.  The blazon is a simple description of the knot’s form.  We have no examples of its use in period armory.

Eilis ni Roibeard O’Bourne bears:  Or, within a quatrefoil knot azure, a rose purpure, barbed and seeded proper.