Triquerta or Triquetra (IPA: [tɹaɪ'kwεtɹə]) is a word 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 certain more complicated shape formed of three vesicae piscis, sometimes with an added circle in or around it.
Celtic Reconstructionist Pagans use the triquetra either to represent one of the various triplicities in their cosmology and theology (such as the tripartite division of the world into the realms of Land, Sea and Sky), or as a symbol of one of the specific triple Goddesses, most notably Brigid, representing the mother, the maid and the crone. Triplicities were in Celtic myth and legend, one of the possible reasons Christian beliefs were so easily adopted by the Celtijmc people.
The symbol is also sometimes used by Wiccans and some New Agers to symbolize either the Wiccan triple goddess, the interconnected parts of our existence (Mind, Body, and Soul), or many other concepts that seem to fit into this idea of a unity.