Reference from Veda
Yantra(Sanskrit) (literally "machine, contraption"[1]) is a mystical
diagram, mainly from the Tantric traditions of the Indian religions. They are used
for the worship of deities in temples or at home; as an aid in meditation; used for
the benefits given by their supposed occult powers based on Hindu astrology and
tantric texts. They are also used for the adornment of temple floors, due mainly
to their aesthetic and symmetric qualities. Specific yantras are traditionally
associated with specific deities.
In Rigvedic Sanskrit, it meant an instrument for restraining or fastening, a prop,
support or barrier, etymologically from the root yam "to sustain, support" and
the -tra suffix expressing instruments. The literal meaning is still evident in the
medical terminology of Sushruta, where the term refers to blunt surgical
instruments such as tweezers or a vice.