Triquetra (pronounced /traɪˈkwɛtrə/) is a noun derived from the Latin tri- ("three") and quetrus ("cornered"). Its original meaning was simply "triangle". Nowadays, it has come to refer exclusively to this more complicated shape: formed of three vesicae piscis, often with an added circle (as seen here). Much like its predecessor: the triangle, it's used to symbolize the power of things and persons that are threefold. Available on most of zazzle's customisable products.