Definition:

 

Triquetra (pronounced /traɪˈkwɛtrə/) is a noun derived from the Latin tri- ("three") and quetrus ("cornered"). Its original meaning was simply "triangle" and it has been used to refer to various three-cornered shapes. Nowadays, it has come to refer exclusively to a particular more complicated shape formed of three vesicae piscis, sometimes with an added circle in or around it. This has been used as a religious symbol of things and persons that are threefold.

 

Celtic Use:

The triquetra is often found in Insular art, most notably metal work and in illuminated manuscripts like the Book of Kells. It is also found in similar artwork on Celtic crosses and slabs from the early Christian period. The fact that the triquetra rarely stood alone in medieval Celtic art has cast reasonable doubt on its use as a primary symbol of belief. In manuscripts it was used primarily as a space filler or ornament in much more complex compositions, and in knotwork panels it is a design motif integrated with other design elements. Celtic art lives on as both a living folk art tradition and through several revivals. This widely recognized knot has been used as a singular symbol for the past two centuries by Celtic Christians, Pagans and agnostics as a sign of special things and persons that are threefold.

 

Christian Use:

The symbol has been used by Christians as a sign of the Trinity (Father, Son and Holy Spirit) especially since the Celtic Revival of the 19th century. When modern designers began to display the triquetra as a stand-alone design it recalled the three-leafed shamrock which was similarly offered as a trinity symbol by Saint Patrick. Some have also suggested that the triquetra has a similarity to the Christian Ιχθυς symbol. The triquetra has been used extensively on Christian sculpture, vestments, book arts and stained glass. It has been used on the title page and binding of some editions of the New King James Version.

A very common representation of the symbol is with a circle that goes through the three interconnected loops of the Triquetra. The circle emphasizes the unity of the whole combination of the three elements.