Quatrefoil

In art, architecture, and traditional Christian symbolism, the quatrefoil is a type of decorative framework consisting of a symmetrical shape which forms the overall outline of four partially overlapping circles of the same diameter. The word quatrefoil means "four leaves", from Latin quattuor, four, plus folium, a leaf.) and applies to general four-lobed shapes in various contexts.
Architecture history
The quatrefoil enjoyed its peak popularity during the Gothic and Renaissance eras. It is most commonly found as tracery, mainly in Gothic architecture, where a quatrefoil often may be seen at the top of a Gothic arch, sometimes filled with stained glass. It’s probable that it has roots in Islamic architecture.
Barbed quatrefoil
The barbed quatrefoil is a quatrefoil pierced at the angles by the points of an inscribed square, which gives an image akin to an heraldic rose, which is termed "barbed" due to the stylised thorns which...